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      Django

      How to Set Up a Scalable Django App with DigitalOcean Managed Databases and Spaces


      Introduction

      Django is a powerful web framework that can help you get your Python application or website off the ground quickly. It includes several convenient features like an object-relational mapper, a Python API, and a customizable administrative interface for your application. It also includes a caching framework and encourages clean app design through its URL Dispatcher and Template system.

      Out of the box, Django includes a minimal web server for testing and local development, but it should be paired with a more robust serving infrastructure for production use cases. Django is often rolled out with an Nginx web server to handle static file requests and HTTPS redirection, and a Gunicorn WSGI server to serve the app.

      In this guide, we will augment this setup by offloading static files like Javascript and CSS stylesheets to DigitalOcean Spaces, and optionally delivering them using a Content Delivery Network, or CDN, which stores these files closer to end users to reduce transfer times. We’ll also use a DigitalOcean Managed PostgreSQL database as our data store to simplify the data layer and avoid having to manually configure a scalable PostgreSQL database.

      Prerequisites

      Before you begin with this guide, you should have the following available to you:

      Step 1 — Installing Packages from the Ubuntu Repositories

      To begin, we’ll download and install all of the items we need from the Ubuntu repositories. We’ll use the Python package manager pip to install additional components a bit later.

      We need to first update the local apt package index and then download and install the packages.

      In this guide, we’ll use Django with Python 3. To install the necessary libraries, log in to your server and type:

      • sudo apt update
      • sudo apt install python3-pip python3-dev libpq-dev curl postgresql-client

      This will install pip, the Python development files needed to build Gunicorn, the libpq header files needed to build the Pyscopg PostgreSQL Python adapter, and the PostgreSQL command-line client.

      Hit Y and then ENTER when prompted to begin downloading and installing the packages.

      Next, we’ll configure the database to work with our Django app.

      Step 2 — Creating the PostgreSQL Database and User

      We’ll now create a database and database user for our Django application.

      To begin, grab the Connection Parameters for your cluster by navigating to Databases from the Cloud Control Panel, and clicking into your database. You should see a Connection Details box containing some parameters for your cluster. Note these down.

      Back on the command line, log in to your cluster using these credentials and the psql PostgreSQL client we just installed:

      • psql -U do_admin -h host -p port -d database

      When prompted, enter the password displayed alongside the doadmin Postgres username, and hit ENTER.

      You will be given a PostgreSQL prompt from which you can manage the database.

      First, create a database for your project called polls:

      Note: Every Postgres statement must end with a semicolon, so make sure that your command ends with one if you are experiencing issues.

      We can now switch to the polls database:

      Next, create a database user for the project. Make sure to select a secure password:

      • CREATE USER myprojectuser WITH PASSWORD 'password';

      We'll now modify a few of the connection parameters for the user we just created. This will speed up database operations so that the correct values do not have to be queried and set each time a connection is established.

      We are setting the default encoding to UTF-8, which Django expects. We are also setting the default transaction isolation scheme to "read committed", which blocks reads from uncommitted transactions. Lastly, we are setting the timezone. By default, our Django projects will be set to use UTC. These are all recommendations from the Django project itself.

      Enter the following commands at the PostgreSQL prompt:

      • ALTER ROLE myprojectuser SET client_encoding TO 'utf8';
      • ALTER ROLE myprojectuser SET default_transaction_isolation TO 'read committed';
      • ALTER ROLE myprojectuser SET timezone TO 'UTC';

      Now we can give our new user access to administer our new database:

      • GRANT ALL PRIVILEGES ON DATABASE polls TO myprojectuser;

      When you are finished, exit out of the PostgreSQL prompt by typing:

      Your Django app is now ready to connect to and manage this database.

      In the next step, we'll install virtualenv and create a Python virtual environment for our Django project.

      Step 3 — Creating a Python Virtual Environment for your Project

      Now that we've set up our database to work with our application, we'll create a Python virtual environment that will isolate this project's dependencies from the system's global Python installation.

      To do this, we first need access to the virtualenv command. We can install this with pip.

      Upgrade pip and install the package by typing:

      • sudo -H pip3 install --upgrade pip
      • sudo -H pip3 install virtualenv

      With virtualenv installed, we can create a directory to store our Python virtual environments and make one to use with the Django polls app.

      Create a directory called envs and navigate into it:

      Within this directory, create a Python virtual environment called polls by typing:

      This will create a directory called polls within the envs directory. Inside, it will install a local version of Python and a local version of pip. We can use this to install and configure an isolated Python environment for our project.

      Before we install our project's Python requirements, we need to activate the virtual environment. You can do that by typing:

      • source polls/bin/activate

      Your prompt should change to indicate that you are now operating within a Python virtual environment. It will look something like this: (polls)user@host:~/envs$.

      With your virtual environment active, install Django, Gunicorn, and the psycopg2 PostgreSQL adaptor with the local instance of pip:

      Note: When the virtual environment is activated (when your prompt has (polls) preceding it), use pip instead of pip3, even if you are using Python 3. The virtual environment's copy of the tool is always named pip, regardless of the Python version.

      • pip install django gunicorn psycopg2-binary

      You should now have all of the software you need to run the Django polls app. In the next step, we'll create a Django project and install this app.

      Step 4 — Creating the Polls Django Application

      We can now set up our sample application. In this tutorial, we'll use the Polls demo application from the Django documentation. It consists of a public site that allows users to view polls and vote in them, and an administrative control panel that allows the admin to modify, create, and delete polls.

      In this guide, we'll skip through the tutorial steps, and simply clone the final application from the DigitalOcean Community django-polls repo.

      If you'd like to complete the steps manually, create a directory called django-polls in your home directory and navigate into it:

      • cd
      • mkdir django-polls
      • cd django-polls

      From there, you can follow the Writing your first Django app tutorial from the official Django documentation. When you're done, skip to Step 5.

      If you just want to clone the finished app, navigate to your home directory and use git to clone the django-polls repo:

      • cd
      • git clone https://github.com/do-community/django-polls.git

      cd into it, and list the directory contents:

      You should see the following objects:

      Output

      LICENSE README.md manage.py mysite polls templates

      manage.py is the main command-line utility used to manipulate the app. polls contains the polls app code, and mysite contains project-scope code and settings. templates contains custom template files for the administrative interface. To learn more about the project structure and files, consult Creating a Project from the official Django documentation.

      Before running the app, we need to adjust its default settings and connect it to our database.

      Step 5 — Adjusting the App Settings

      In this step, we'll modify the Django project's default configuration to increase security, connect Django to our database, and collect static files into a local directory.

      Begin by opening the settings file in your text editor:

      • nano ~/django-polls/mysite/settings.py

      Start by locating the ALLOWED_HOSTS directive. This defines a list of the addresses or domain names that you want to use to connect to the Django instance. An incoming request with a Host header not in this list will raise an exception. Django requires that you set this to prevent a certain class of security vulnerability.

      In the square brackets, list the IP addresses or domain names associated with your Django server. Each item should be listed in quotations with entries separated by a comma. Your list will also include localhost, since you will be proxying connections through a local Nginx instance. If you wish to include requests for an entire domain and any subdomains, prepend a period to the beginning of the entry.

      In the snippet below, there are a few commented out examples that demonstrate what these entries should look like:

      ~/django-polls/mysite/settings.py

      . . .
      
      # The simplest case: just add the domain name(s) and IP addresses of your Django server
      # ALLOWED_HOSTS = [ 'example.com', '203.0.113.5']
      # To respond to 'example.com' and any subdomains, start the domain with a dot
      # ALLOWED_HOSTS = ['.example.com', '203.0.113.5']
      ALLOWED_HOSTS = ['your_server_domain_or_IP', 'second_domain_or_IP', . . ., 'localhost']
      
      . . . 
      

      Next, find the section of the file that configures database access. It will start with DATABASES. The configuration in the file is for a SQLite database. We already created a PostgreSQL database for our project, so we need to adjust these settings.

      We will tell Django to use the psycopg2 database adaptor we installed with pip, instead of the default SQLite engine. We’ll also reuse the Connection Parameters referenced in Step 2. You can always find this information from the Managed Databases section of the DigitalOcean Cloud Control Panel.

      Update the file with your database settings: the database name (polls), the database username, the database user's password, and the database host and port. Be sure to replace the database-specific values with your own information:

      ~/django-polls/mysite/settings.py

      . . .
      
      DATABASES = {
          'default': {
              'ENGINE': 'django.db.backends.postgresql_psycopg2',
              'NAME': 'polls',
              'USER': 'myprojectuser',
              'PASSWORD': 'password',
              'HOST': 'managed_db_host',
              'PORT': 'managed_db_port',
          }
      }
      
      . . .
      

      Next, move down to the bottom of the file and add a setting indicating where the static files should be placed. This is necessary so that Nginx can handle requests for these items. The following line tells Django to place them in a directory called static in the base project directory:

      ~/django-polls/mysite/settings.py

      . . .
      
      STATIC_URL = '/static/'
      STATIC_ROOT = os.path.join(BASE_DIR, 'static/')
      

      Save and close the file when you are finished.

      At this point, you've configured the Django project's database, security, and static files settings. If you followed the polls tutorial from the start and did not clone the GitHub repo, you can move on to Step 6. If you cloned the GitHub repo, there remains one additional step.

      The Django settings file contains a SECRET_KEY variable that is used to create hashes for various Django objects. It's important that it is set to a unique, unpredictable value. The SECRET_KEY variable has been scrubbed from the GitHub repository, so we'll create a new one using a function built-in to the django Python package called get_random_secret_key(). From the command line, open up a Python interpreter:

      You should see the following output and prompt:

      Output

      Python 3.6.7 (default, Oct 22 2018, 11:32:17) [GCC 8.2.0] on linux Type "help", "copyright", "credits" or "license" for more information. >>>

      Import the get_random_secret_key function from the Django package, then call the function:

      • from django.core.management.utils import get_random_secret_key
      • get_random_secret_key()

      Copy the resulting key to your clipboard.

      Exit the Python interpreter by pressing CTRL+D.

      Next, open up the settings file in your text editor once again:

      nano ~/django-polls/mysite/settings.py
      

      Locate the SECRET_KEY variable and paste in the key you just generated:

      ~/django-polls/mysite/settings.py

      . . .
      
      # SECURITY WARNING: keep the secret key used in production secret!
      SECRET_KEY = 'your_secret_key_here'
      
      . . .
      

      Save and close the file.

      We'll now test the app locally using the Django development server to ensure that everything's been correctly configured.

      Step 6 — Testing the App

      Before we run the Django development server, we need to use the manage.py utility to create the database schema and collect static files into the STATIC_ROOT directory.

      Navigate into the project's base directory, and create the initial database schema in our PostgreSQL database using the makemigrations and migrate commands:

      • cd django-polls
      • ./manage.py makemigrations
      • ./manage.py migrate

      makemigrations will create the migrations, or database schema changes, based on the changes made to Django models. migrate will apply these migrations to the database schema. To learn more about migrations in Django, consult Migrations from the official Django documentation.

      Create an administrative user for the project by typing:

      • ./manage.py createsuperuser

      You will have to select a username, provide an email address, and choose and confirm a password.

      We can collect all of the static content into the directory location we configured by typing:

      • ./manage.py collectstatic

      The static files will then be placed in a directory called static within your project directory.

      If you followed the initial server setup guide, you should have a UFW firewall protecting your server. In order to test the development server, we'll have to allow access to the port we'll be using.

      Create an exception for port 8000 by typing:

      Testing the App Using the Django Development Server

      Finally, you can test your project by starting the Django development server with this command:

      • ./manage.py runserver 0.0.0.0:8000

      In your web browser, visit your server's domain name or IP address followed by :8000 and the polls path:

      • http://server_domain_or_IP:8000/polls

      You should see the Polls app interface:

      Polls App Interface

      To check out the admin interface, visit your server's domain name or IP address followed by :8000 and the administrative interface's path:

      • http://server_domain_or_IP:8000/admin

      You should see the Polls app admin authentication window:

      Polls Admin Auth Page

      Enter the administrative username and password you created with the createsuperuser command.

      After authenticating, you can access the Polls app's administrative interface:

      Polls Admin Main Interface

      When you are finished exploring, hit CTRL-C in the terminal window to shut down the development server.

      Testing the App Using Gunicorn

      The last thing we want to do before offloading static files is test Gunicorn to make sure that it can serve the application. We can do this by entering our project directory and using gunicorn to load the project's WSGI module:

      • gunicorn --bind 0.0.0.0:8000 mysite.wsgi

      This will start Gunicorn on the same interface that the Django development server was running on. You can go back and test the app again.

      Note: The admin interface will not have any of the styling applied since Gunicorn does not know how to find the static CSS content responsible for this.

      We passed Gunicorn a module by specifying the relative directory path to Django's wsgi.py file, the entry point to our application,. This file defines a function called application, which communicates with the application. To learn more about the WSGI specification, click here.

      When you are finished testing, hit CTRL-C in the terminal window to stop Gunicorn.

      We'll now offload the application’s static files to DigitalOcean Spaces.

      Step 7 — Offloading Static Files to DigitalOcean Spaces

      At this point, Gunicorn can serve our Django application but not its static files. Usually we'd configure Nginx to serve these files, but in this tutorial we'll offload them to DigitalOcean Spaces using the django-storages plugin. This allows you to easily scale Django by centralizing its static content and freeing up server resources. In addition, you can deliver this static content using the DigitalOcean Spaces CDN.

      For a full guide on offloading Django static files to Object storage, consult How to Set Up Object Storage with Django.

      Installing and Configuring django-storages

      We'll begin by installing the django-storages Python package. The django-storages package provides Django with the S3Boto3Storage storage backend that uses the boto3 library to upload files to any S3-compatible object storage service.

      To start, install thedjango-storages and boto3 Python packages using pip:

      • pip install django-storages boto3

      Next, open your app's Django settings file again:

      • nano ~/django-polls/mysite/settings.py

      Navigate down to the INSTALLED_APPS section of the file, and append storages to the list of installed apps:

      ~/django-polls/mysite/settings.py

      . . .
      
      INSTALLED_APPS = [
          . . .
          'django.contrib.staticfiles',
          'storages',
      ]
      
      . . .
      

      Scroll further down the file to the STATIC_URL we previously modified. We'll now overwrite these values and append new S3Boto3Storage backend parameters. Delete the code you entered earlier, and add the following blocks, which include access and location information for your Space. Remember to replace the highlighted values here with your own information::

      ~/django-polls/mysite/settings.py

      . . .
      
      # Static files (CSS, JavaScript, Images)
      # https://docs.djangoproject.com/en/2.1/howto/static-files/
      
      AWS_ACCESS_KEY_ID = 'your_spaces_access_key'
      AWS_SECRET_ACCESS_KEY = 'your_spaces_secret_key'
      
      AWS_STORAGE_BUCKET_NAME = 'your_space_name'
      AWS_S3_ENDPOINT_URL = 'spaces_endpoint_URL'
      AWS_S3_OBJECT_PARAMETERS = {
          'CacheControl': 'max-age=86400',
      }
      AWS_LOCATION = 'static'
      AWS_DEFAULT_ACL = 'public-read'
      
      STATICFILES_STORAGE = 'storages.backends.s3boto3.S3Boto3Storage'
      
      STATIC_URL = '{}/{}/'.format(AWS_S3_ENDPOINT_URL, AWS_LOCATION)
      STATIC_ROOT = 'static/'
      

      We define the following configuration items:

      • AWS_ACCESS_KEY_ID: The Access Key ID for the Space, which you created in the tutorial prerequisites. If you didn’t create a set of Access Keys, consult Sharing Access to Spaces with Access Keys.
      • AWS_SECRET_ACCESS_KEY: The secret key for the DigitalOcean Space.
      • AWS_STORAGE_BUCKET_NAME: Your DigitalOcean Space name.
      • AWS_S3_ENDPOINT_URL : The endpoint URL used to access the object storage service. For DigitalOcean, this will be something like https://nyc3.digitaloceanspaces.com depending on the Space region.
      • AWS_S3_OBJECT_PARAMETERS Sets the cache control headers on static files.
      • AWS_LOCATION: Defines a directory within the object storage bucket where all static files will be placed.
      • AWS_DEFAULT_ACL: Defines the access control list (ACL) for the static files. Setting it to public-read ensures that the files are publicly accessible to end users.
      • STATICFILES_STORAGE: Sets the storage backend Django will use to offload static files. This backend should work with any S3-compatible backend, including DigitalOcean Spaces.
      • STATIC_URL: Specifies the base URL that Django should use when generating URLs for static files. Here, we combine the endpoint URL and the static files subdirectory to construct a base URL for static files.
      • STATIC_ROOT: Specifies where to collect static files locally before copying them to object storage.

      From now on, when you run collectstatic, Django will upload your app's static files to the Space. When you start Django, it'll begin serving static assets like CSS and Javascript from this Space.

      Before we test that this is all functioning correctly, we need to configure Cross-Origin Resource Sharing (CORS) headers for our Spaces files or access to certain static assets may be denied by your web browser.

      CORS headers tell the web browser that the an application running at one domain can access scripts or resources located at another. In this case, we need to allow cross-origin resource sharing for our Django server's domain so that requests for static files in the Space are not denied by the web browser.

      To begin, navigate to the Settings page of your Space using the Cloud Control Panel:

      Screenshot of the Settings tab

      In the CORS Configurations section, click Add.

      CORS advanced settings

      Here, under Origin, enter the wildcard origin, *

      Warning: When you deploy your app into production, be sure to change this value to your exact origin domain (including the http:// or https:// protocol). Leaving this as the wildcard origin is insecure, and we do this here only for testing purposes since setting the origin to http://example.com:8000 (using a nonstandard port) is currently not supported.

      Under Allowed Methods, select GET.

      Click on Add Header, and in text box that appears, enter Access-Control-Allow-Origin.

      Set Access Control Max Age to 600 so that the header we just created expires every 10 minutes.

      Click Save Options.

      From now on, objects in your Space will contain the appropriate Access-Control-Allow-Origin response headers, allowing modern secure web browsers to fetch these files across domains.

      At this point, you can optionally enable the CDN for your Space, which will serve these static files from a distributed network of edge servers. To learn more about CDNs, consult Using a CDN to Speed Up Static Content Delivery. This can significantly improve web performance. If you don't want to enable the CDN for your Space, skip ahead to the next section, Testing Spaces Static File Delivery.

      Enabling CDN (Optional)

      To activate static file delivery via the DigitalOcean Spaces CDN, begin by enabling the CDN for your DigitalOcean Space. To learn how to do this, consult How to Enable the Spaces CDN from the DigitalOcean product documentation.

      Once you've enabled the CDN for your Space, navigate to it using the Cloud Control Panel. You should see a new Endpoints link under your Space name:

      List of Space Endpoints

      These endpoints should contain your Space name.

      Notice the addition of a new Edge endpoint. This endpoint routes requests for Spaces objects through the CDN, serving them from the edge cache as much as possible. Note down this Edge endpoint, as we'll use it to configure the django-storages plugin.

      Next, edit your app's Django settings file once again:

      • nano ~/django-polls/mysite/settings.py

      Navigate down to the Static Files section we recently modified. Add the AWS_S3_CUSTOM_DOMAIN parameter to configure the django-storages plugin CDN endpoint and update the STATIC_URL parameter to use this new CDN endpoint:

      ~/django-polls/mysite/settings.py

      . . .
      
      # Static files (CSS, JavaScript, Images)
      # https://docs.djangoproject.com/en/2.1/howto/static-files/
      
      # Moving static assets to DigitalOcean Spaces as per:
      # https://www.digitalocean.com/community/tutorials/how-to-set-up-object-storage-with-django
      AWS_ACCESS_KEY_ID = 'your_spaces_access_key'
      AWS_SECRET_ACCESS_KEY = 'your_spaces_secret_key'
      
      AWS_STORAGE_BUCKET_NAME = 'your_space_name'
      AWS_S3_ENDPOINT_URL = 'spaces_endpoint_URL'
      AWS_S3_CUSTOM_DOMAIN = 'spaces_edge_endpoint_URL'
      AWS_S3_OBJECT_PARAMETERS = {
          'CacheControl': 'max-age=86400',
      }
      AWS_LOCATION = 'static'
      AWS_DEFAULT_ACL = 'public-read'
      
      STATICFILES_STORAGE = 'storages.backends.s3boto3.S3Boto3Storage'
      
      STATIC_URL = '{}/{}/'.format(AWS_S3_CUSTOM_DOMAIN, AWS_LOCATION)
      STATIC_ROOT = 'static/'
      

      Here, replace the spaces_edge_endpoint_URL with the Edge endpoint you just noted down, truncating the https:// prefix. For example, if the Edge endpoint URL is https://example.sfo2.cdn.digitaloceanspaces.com, AWS_S3_CUSTOM_DOMAIN should be set to example.sfo2.cdn.digitaloceanspaces.com.

      When you're done, save and close the file.

      When you start Django, it will now serve static content using the CDN for your DigitalOcean Space.

      Testing Spaces Static File Delivery

      We'll now test that Django is correctly serving static files from our DigitalOcean Space.

      Navigate to your Django app directory:

      From here, run collectstatic to collect and upload static files to your DigitalOcean Space:

      • python manage.py collectstatic

      You should see the following output:

      Output

      You have requested to collect static files at the destination location as specified in your settings. This will overwrite existing files! Are you sure you want to do this? Type 'yes' to continue, or 'no' to cancel:

      Type yes and hit ENTER to confirm.

      You should then see output like the following

      Output

      121 static files copied.

      This confirms that Django successfully uploaded the polls app static files to your Space. You can navigate to your Space using the Cloud Control Panel, and inspect the files in the static directory.

      Next, we'll verify that Django is rewriting the appropriate URLs.

      Start the Gunicorn server:

      • gunicorn --bind 0.0.0.0:8000 mysite.wsgi

      In your web browser, visit your server's domain name or IP address followed by :8000 and /admin:

      http://server_domain_or_IP:8000/admin
      

      You should once again see the Polls app admin authentication window, this time with correct styling.

      Now, use your browser's developer tools to inspect the page contents and reveal the source file storage locations.

      To do this using Google Chrome, right-click the page, and select Inspect.

      You should see the following window:

      Chrome Dev Tools Window

      From here, click on Sources in the toolbar. In the list of source files in the left-hand pane, you should see /admin/login under your Django server's domain, and static/admin under your Space's CDN endpoint. Within static/admin, you should see both the css and fonts directories.

      This confirms that CSS stylesheets and fonts are correctly being served from your Space's CDN.

      When you are finished testing, hit CTRL-C in the terminal window to stop Gunicorn.

      You can disable your active Python virtual environment by entering deactivate:

      Your prompt should return to normal.

      At this point you've successfully offloaded static files from your Django server, and are serving them from object storage. We can now move on to configuring Gunicorn to start automatically as a system service.

      Step 8 — Creating systemd Socket and Service Files for Gunicorn

      In Step 6 we tested that Gunicorn can interact with our Django application, but we should implement a more robust way of starting and stopping the application server. To accomplish this, we'll make systemd service and socket files.

      The Gunicorn socket will be created at boot and will listen for connections. When a connection occurs, systemd will automatically start the Gunicorn process to handle the connection.

      Start by creating and opening a systemd socket file for Gunicorn with sudo privileges:

      • sudo nano /etc/systemd/system/gunicorn.socket

      Inside, we will create a [Unit] section to describe the socket, a [Socket] section to define the socket location, and an [Install] section to make sure the socket is created at the right time. Add the following code to the file:

      /etc/systemd/system/gunicorn.socket

      [Unit]
      Description=gunicorn socket
      
      [Socket]
      ListenStream=/run/gunicorn.sock
      
      [Install]
      WantedBy=sockets.target
      

      Save and close the file when you are finished.

      Next, create and open a systemd service file for Gunicorn with sudo privileges in your text editor. The service filename should match the socket filename with the exception of the extension:

      • sudo nano /etc/systemd/system/gunicorn.service

      Start with the [Unit] section, which specifies metadata and dependencies. We'll put a description of our service here and tell the init system to only start this after the networking target has been reached. Because our service relies on the socket from the socket file, we need to include a Requires directive to indicate that relationship:

      /etc/systemd/system/gunicorn.service

      [Unit]
      Description=gunicorn daemon
      Requires=gunicorn.socket
      After=network.target
      

      Next, we'll open up the [Service] section. We'll specify the user and group that we want to process to run under. We will give our regular user account ownership of the process since it owns all of the relevant files. We'll give group ownership to the www-data group so that Nginx can communicate easily with Gunicorn.

      We'll then map out the working directory and specify the command to use to start the service. In this case, we'll have to specify the full path to the Gunicorn executable, which is installed within our virtual environment. We will bind the process to the Unix socket we created within the /run directory so that the process can communicate with Nginx. We log all data to standard output so that the journald process can collect the Gunicorn logs. We can also specify any optional Gunicorn tweaks here, like the number of worker processes. Here, we run Gunicorn with 3 worker processes.

      Add the following Service section to the file. Be sure to replace the username listed here with your own username:

      /etc/systemd/system/gunicorn.service

      [Unit]
      Description=gunicorn daemon
      Requires=gunicorn.socket
      After=network.target
      
      [Service]
      User=sammy
      Group=www-data
      WorkingDirectory=/home/sammy/django-polls
      ExecStart=/home/sammy/envs/polls/bin/gunicorn 
                --access-logfile - 
                --workers 3 
                --bind unix:/run/gunicorn.sock 
                mysite.wsgi:application
      

      Finally, we'll add an [Install] section. This will tell systemd what to link this service to if we enable it to start at boot. We want this service to start when the regular multi-user system is up and running:

      /etc/systemd/system/gunicorn.service

      [Unit]
      Description=gunicorn daemon
      Requires=gunicorn.socket
      After=network.target
      
      [Service]
      User=sammy
      Group=www-data
      WorkingDirectory=/home/sammy/django-polls
      ExecStart=/home/sammy/envs/polls/bin/gunicorn 
                --access-logfile - 
                --workers 3 
                --bind unix:/run/gunicorn.sock 
                mysite.wsgi:application
      
      [Install]
      WantedBy=multi-user.target
      

      With that, our systemd service file is complete. Save and close it now.

      We can now start and enable the Gunicorn socket. This will create the socket file at /run/gunicorn.sock now and at boot. When a connection is made to that socket, systemd will automatically start the gunicorn.service to handle it:

      • sudo systemctl start gunicorn.socket
      • sudo systemctl enable gunicorn.socket

      We can confirm that the operation was successful by checking for the socket file.

      Checking for the Gunicorn Socket File

      Check the status of the process to find out whether it started successfully:

      • sudo systemctl status gunicorn.socket

      You should see the following output:

      Output

      Failed to dump process list, ignoring: No such file or directory ● gunicorn.socket - gunicorn socket Loaded: loaded (/etc/systemd/system/gunicorn.socket; enabled; vendor preset: enabled) Active: active (running) since Tue 2019-03-05 19:19:16 UTC; 1h 22min ago Listen: /run/gunicorn.sock (Stream) CGroup: /system.slice/gunicorn.socket Mar 05 19:19:16 django systemd[1]: Listening on gunicorn socket.

      Next, check for the existence of the gunicorn.sock file within the /run directory:

      Output

      /run/gunicorn.sock: socket

      If the systemctl status command indicated that an error occurred, or if you do not find the gunicorn.sock file in the directory, it's an indication that the Gunicorn socket was not created correctly. Check the Gunicorn socket's logs by typing:

      • sudo journalctl -u gunicorn.socket

      Take another look at your /etc/systemd/system/gunicorn.socket file to fix any problems before continuing.

      Testing Socket Activation

      Currently, if you've only started the gunicorn.socket unit, the gunicorn.service will not be active, since the socket has not yet received any connections. You can check this by typing:

      • sudo systemctl status gunicorn

      Output

      ● gunicorn.service - gunicorn daemon Loaded: loaded (/etc/systemd/system/gunicorn.service; disabled; vendor preset: enabled) Active: inactive (dead)

      To test the socket activation mechanism, we can send a connection to the socket through curl by typing:

      • curl --unix-socket /run/gunicorn.sock localhost

      You should see the HTML output from your application in the terminal. This indicates that Gunicorn has started and is able to serve your Django application. You can verify that the Gunicorn service is running by typing:

      • sudo systemctl status gunicorn

      Output

      ● gunicorn.service - gunicorn daemon Loaded: loaded (/etc/systemd/system/gunicorn.service; disabled; vendor preset: enabled) Active: active (running) since Tue 2019-03-05 20:43:56 UTC; 1s ago Main PID: 19074 (gunicorn) Tasks: 4 (limit: 4915) CGroup: /system.slice/gunicorn.service ├─19074 /home/sammy/envs/polls/bin/python3 /home/sammy/envs/polls/bin/gunicorn --access-logfile - --workers 3 --bind unix:/run/gunicorn.sock mysite.wsgi:application ├─19098 /home/sammy/envs/polls/bin/python3 /home/sammy/envs/polls/bin/gunicorn . . . Mar 05 20:43:56 django systemd[1]: Started gunicorn daemon. Mar 05 20:43:56 django gunicorn[19074]: [2019-03-05 20:43:56 +0000] [19074] [INFO] Starting gunicorn 19.9.0 . . . Mar 05 20:44:15 django gunicorn[19074]: - - [05/Mar/2019:20:44:15 +0000] "GET / HTTP/1.1" 301 0 "-" "curl/7.58.0"

      If the output from curl or the output of systemctl status indicates that a problem occurred, check the logs for additional details:

      • sudo journalctl -u gunicorn

      You can also check your /etc/systemd/system/gunicorn.service file for problems. If you make changes to this file, be sure to reload the daemon to reread the service definition and restart the Gunicorn process:

      • sudo systemctl daemon-reload
      • sudo systemctl restart gunicorn

      Make sure you troubleshoot any issues before continuing on to configuring the Nginx server.

      Step 8 — Configuring Nginx HTTPS and Gunicorn Proxy Passing

      Now that Gunicorn is set up in a more robust fashion, we need to configure Nginx to encrypt connections and hand off traffic to the Gunicorn process.

      If you followed the preqrequisites and set up Nginx with Let's Encrypt, you should already have a server block file corresponding to your domain available to you in Nginx's sites-available directory. If not, follow How To Secure Nginx with Let's Encrypt on Ubuntu 18.04 and return to this step.

      Before we edit this example.com server block file, we’ll first remove the default server block file that gets rolled out by default after installing Nginx:

      • sudo rm /etc/nginx/sites-enabled/default

      We'll now modify the example.com server block file to pass traffic to Gunicorn instead of the default index.html page configured in the prerequisite step.

      Open the server block file corresponding to your domain in your editor:

      • sudo nano /etc/nginx/sites-available/example.com

      You should see something like the following:

      /etc/nginx/sites-available/example.com

      server {
      
              root /var/www/example.com/html;
              index index.html index.htm index.nginx-debian.html;
      
              server_name example.com www.example.com;
      
              location / {
                      try_files $uri $uri/ =404;
              }
      
          listen [::]:443 ssl ipv6only=on; # managed by Certbot
          listen 443 ssl; # managed by Certbot
          ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
          ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot
          include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
          ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
      
      }
      
      server {
          if ($host = example.com) {
              return 301 https://$host$request_uri;
          } # managed by Certbot
      
      
              listen 80;
              listen [::]:80;
      
              server_name example.com www.example.com;
          return 404; # managed by Certbot
      
      
      }
      

      This is a combination of the default server block file created in How to Install Nginx on Ubuntu 18.04 as well as additions appended automatically by Let's Encrypt. We are going to delete the contents of this file and write a new configuration that redirects HTTP traffic to HTTPS, and forwards incoming requests to the Gunicorn socket we created in the previous step.

      If you'd like, you can make a backup of this file using cp. Quit your text editor and create a backup called example.com.old:

      • sudo cp /etc/nginx/sites-available/example.com /etc/nginx/sites-available/example.com.old

      Now, reopen the file and delete its contents. We'll build the new configuration block by block.

      Begin by pasting in the following block, which redirects HTTP requests at port 80 to HTTPS:

      /etc/nginx/sites-available/example.com

      server {
          listen 80 default_server;
          listen [::]:80 default_server;
          server_name _;
          return 301 https://example.com$request_uri;
      }
      

      Here we listen for HTTP IPv4 and IPv6 requests on port 80 and send a 301 response header to redirect the request to HTTPS port 443 using the example.com domain. This will also redirect direct HTTP requests to the server’s IP address.

      After this block, append the following block of config code that handles HTTPS requests for the example.com domain:

      /etc/nginx/sites-available/example.com

      . . . 
      server {
          listen [::]:443 ssl ipv6only=on;
          listen 443 ssl;
          server_name example.com www.example.com;
      
          # Let's Encrypt parameters
          ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
          ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
          include /etc/letsencrypt/options-ssl-nginx.conf;
          ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
      
          location = /favicon.ico { access_log off; log_not_found off; }
      
          location / {
              proxy_pass         http://unix:/run/gunicorn.sock;
              proxy_redirect     off;
      
              proxy_set_header   Host              $http_host;
              proxy_set_header   X-Real-IP         $remote_addr;
              proxy_set_header   X-Forwarded-For   $proxy_add_x_forwarded_for;
              proxy_set_header   X-Forwarded-Proto https;
          }
      }
      

      Here, we first listen on port 443 for requests hitting the example.com and www.example.com domains.

      Next, we provide the same Let's Encrypt configuration included in the default server block file, which specifies the location of the SSL certificate and private key, as well as some additional security parameters.

      The location = /favicon.ico line instructs Nginx to ignore any problems with finding a favicon.

      The last location = / block instructs Nginx to hand off requests to the Gunicorn socket configured in Step 8. In addition, it adds headers to inform the upstream Django server that a request has been forwarded and to provide it with various request properties.

      After you've pasted in those two configuration blocks, the final file should look something like this:

      /etc/nginx/sites-available/example.com

      server {
          listen 80 default_server;
          listen [::]:80 default_server;
          server_name _;
          return 301 https://example.com$request_uri;
      }
      server {
              listen [::]:443 ssl ipv6only=on;
              listen 443 ssl;
              server_name example.com www.example.com;
      
              # Let's Encrypt parameters
              ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
              ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
              include /etc/letsencrypt/options-ssl-nginx.conf;
              ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;
      
              location = /favicon.ico { access_log off; log_not_found off; }
      
              location / {
                proxy_pass         http://unix:/run/gunicorn.sock;
                proxy_redirect     off;
      
                proxy_set_header   Host              $http_host;
                proxy_set_header   X-Real-IP         $remote_addr;
                proxy_set_header   X-Forwarded-For   $proxy_add_x_forwarded_for;
                proxy_set_header   X-Forwarded-Proto https;
              }
      }
      

      Save and close the file when you are finished.

      Test your Nginx configuration for syntax errors by typing:

      If your configuration is error-free, restart Nginx by typing:

      • sudo systemctl restart nginx

      You should now be able to visit your server's domain or IP address to view your application. Your browser should be using a secure HTTPS connection to connect to the Django backend.

      To completely secure our Django project, we need to add a couple of security parameters to its settings.py file. Reopen this file in your editor:

      • nano ~/django-polls/mysite/settings.py

      Scroll to the bottom of the file, and add the following parameters:

      ~/django-polls/mysite/settings.py

      . . .
      
      SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')
      SESSION_COOKIE_SECURE = True
      CSRF_COOKIE_SECURE = True
      SECURE_SSL_REDIRECT = True
      

      These settings tell Django that you have enabled HTTPS on your server, and instruct it to use "secure" cookies. To learn more about these settings, consult the SSL/HTTPS section of Security in Django.

      When you're done, save and close the file.

      Finally, restart Gunicorn:

      • sudo systemctl restart gunicorn

      At this point, you have configured Nginx to redirect HTTP requests and hand off these requests to Gunicorn. HTTPS should now be fully enabled for your Django project and app. If you're running into errors, this discussion on troubleshooting Nginx and Gunicorn may help.

      Warning: As stated in Configuring CORS Headers, be sure to change the Origin from the wildcard * domain to your domain name (https://example.com in this guide) before making your app accessible to end users.

      Conclusion

      In this guide, you set up and configured a scalable Django application running on an Ubuntu 18.04 server. This setup can be replicated across multiple servers to create a highly-available architecture. Furthermore, this app and its config can be containerized using Docker or another container runtime to ease deployment and scaling. These containers can then be deployed into a container cluster like Kubernetes. In an upcoming Tutorial series, we will explore how to containerize and modernize this Django polls app so that it can run in a Kubernetes cluster.

      In addition to static files, you may also wish to offload your Django Media files to object storage. To learn how to do this, consult Using Amazon S3 to Store your Django Site's Static and Media Files. You might also consider compressing static files to further optimize their delivery to end users. To do this, you can use a Django plugin like Django compressor.



      Source link

      How To Send Web Push Notifications from Django Applications


      The author selected the Open Internet/Free Speech Fund to receive a donation as part of the Write for DOnations program.

      Introduction

      The web is constantly evolving, and it can now achieve functionalities that were formerly only available on native mobile devices. The introduction of JavaScript service workers gave the web newfound abilities to do things like background syncing, offline caching, and sending push notifications.

      Push notifications allow users to opt-in to receive updates to mobile and web applications. They also enable users to re-engage with existing applications using customized and relevant content.

      In this tutorial, you’ll set up a Django application on Ubuntu 18.04 that sends push notifications whenever there’s an activity that requires the user to visit the application. To create these notifications, you will use the Django-Webpush package and set up and register a service worker to display notifications to the client. The working application with notifications will look like this:

      Web push final

      Prerequisites

      Before you begin this guide you’ll need the following:

      Step 1 — Installing Django-Webpush and Getting Vapid Keys

      Django-Webpush is a package that enables developers to integrate and send web push notifications in Django applications. We’ll use this package to trigger and send push notifications from our application. In this step, you will install Django-Webpush and obtain the Voluntary Application Server Identification (VAPID) keys that are necessary for identifying your server and ensuring the uniqueness of each request.

      Make sure you are in the ~/djangopush project directory that you created in the prerequisites:

      Activate your virtual environment:

      • source my_env/bin/activate

      Upgrade your version of pip to ensure it's up-to-date:

      • pip install --upgrade pip

      Install Django-Webpush:

      • pip install django-webpush

      After installing the package, add it to the list of applications in your settings.py file. First open settings.py:

      • nano ~/djangopush/djangopush/settings.py

      Add webpush to the list of INSTALLED_APPS:

      ~/djangopush/djangopush/settings.py

      ...
      
      INSTALLED_APPS = [
          ...,
          'webpush',
      ]
      ...
      

      Save the file and exit your editor.

      Run migrations on the application to apply the changes you've made to your database schema:

      The output will look like this, indicating a successful migration:

      Output

      Operations to perform: Apply all migrations: admin, auth, contenttypes, sessions, webpush Running migrations: Applying webpush.0001_initial... OK

      The next step in setting up web push notifications is getting VAPID keys. These keys identify the application server and can be used to reduce the secrecy for push subscription URLs, since they restrict subscriptions to a specific server.

      To obtain VAPID keys, navigate to the wep-push-codelab web application. Here, you'll be given automatically generated keys. Copy the private and public keys.

      Next, create a new entry in settings.py for your VAPID information. First, open the file:

      • nano ~/djangopush/djangopush/settings.py

      Next, add a new directive called WEBPUSH_SETTINGS with your VAPID public and private keys and your email below AUTH_PASSWORD_VALIDATORS:

      ~/djangopush/djangopush/settings.py

      ...
      
      AUTH_PASSWORD_VALIDATORS = [
          ...
      ]
      
      WEBPUSH_SETTINGS = {
         "VAPID_PUBLIC_KEY": "your_vapid_public_key",
         "VAPID_PRIVATE_KEY": "your_vapid_private_key",
         "VAPID_ADMIN_EMAIL": "admin@example.com"
      }
      
      # Internationalization
      # https://docs.djangoproject.com/en/2.0/topics/i18n/
      
      ...
      

      Don't forget to replace the placeholder values your_vapid_public_key, your_vapid_private_key, and admin@example.com with your own information. Your email address is how you will be notified if the push server experiences any issues.

      Next, we'll set up views that will display the application's home page and trigger push notifications to subscribed users.

      Step 2 — Setting Up Views

      In this step, we'll setup a basic home view with the HttpResponse response object for our home page, along with a send_push view. Views are functions that return response objects from web requests. The send_push view will use the Django-Webpush library to send push notifications that contain the data entered by a user on the home page.

      Navigate to the ~/djangopush/djangopush folder:

      • cd ~/djangopush/djangopush

      Running ls inside the folder will show you the project's main files:

      Output

      /__init__.py /settings.py /urls.py /wsgi.py

      The files in this folder are auto-generated by the django-admin utility that you used to create your project in the prerequisites. The settings.py file contains project-wide configurations like installed applications and the static root folder. The urls.py file contains the URL configurations for the project. This is where you will set up routes to match your created views.

      Create a new file inside the ~/djangopush/djangopush directory called views.py, which will contain the views for your project:

      • nano ~/djangopush/djangopush/views.py

      The first view we'll make is the home view, which will display the home page where users can send push notifications. Add the following code to the file:

      ~/djangopush/djangopush/views.py

      from django.http.response import HttpResponse
      from django.views.decorators.http import require_GET
      
      @require_GET
      def home(request):
          return HttpResponse('<h1>Home Page<h1>')
      

      The home view is decorated by the require_GET decorator, which restricts the view to GET requests only. A view typically returns a response for every request made to it. This view returns a simple HTML tag as a response.

      The next view we'll create is send_push, which will handle sent push notifications using the django-webpush package. It will be restricted to POST requests only and will be exempted from Cross Site Request Forgery (CSRF) protection. Doing this will allow you to test the view using Postman or any other RESTful service. In production, however, you should remove this decorator to avoid leaving your views vulnerable to CSRF.

      To create the send_push view, first add the following imports to enable JSON responses and access the send_user_notification function in the webpush library:

      ~/djangopush/djangopush/views.py

      from django.http.response import JsonResponse, HttpResponse
      from django.views.decorators.http import require_GET, require_POST
      from django.shortcuts import get_object_or_404
      from django.contrib.auth.models import User
      from django.views.decorators.csrf import csrf_exempt
      from webpush import send_user_notification
      import json
      

      Next, add the require_POST decorator, which will use the request body sent by the user to create and trigger a push notification:

      ~/djangopush/djangopush/views.py

      @require_GET
      def home(request):
          ...
      
      
      @require_POST
      @csrf_exempt
      def send_push(request):
          try:
              body = request.body
              data = json.loads(body)
      
              if 'head' not in data or 'body' not in data or 'id' not in data:
                  return JsonResponse(status=400, data={"message": "Invalid data format"})
      
              user_id = data['id']
              user = get_object_or_404(User, pk=user_id)
              payload = {'head': data['head'], 'body': data['body']}
              send_user_notification(user=user, payload=payload, ttl=1000)
      
              return JsonResponse(status=200, data={"message": "Web push successful"})
          except TypeError:
              return JsonResponse(status=500, data={"message": "An error occurred"})
      

      We are using two decorators for the send_push view: the require_POST decorator, which restricts the view to POST requests only, and the csrf_exempt decorator, which exempts the view from CSRF protection.

      This view expects POST data and does the following: it gets the body of the request and, using the json package, deserializes the JSON document to a Python object using json.loads. json.loads takes a structured JSON document and converts it to a Python object.

      The view expects the request body object to have three properties:

      • head: The title of the push notification.
      • body: The body of the notification.
      • id: The id of the request user.

      If any of the required properties are missing, the view will return a JSONResponse with a 404 "Not Found" status. If the user with the given primary key exists, the view will return the user with the matching primary key using the get_object_or_404 function from the django.shortcuts library. If the user doesn't exist, the function will return a 404 error.

      The view also makes use of the send_user_notification function from the webpush library. This function takes three parameters:

      • User: The recipient of the push notification.
      • payload: The notification information, which includes the notification head and body.
      • ttl: The maximum time in seconds that the notification should be stored if the user is offline.

      If no errors occur, the view returns a JSONResponse with a 200 "Success" status and a data object. If a KeyError occurs, the view will return a 500 "Internal Server Error" status. A KeyError occurs when the requested key of an object doesn't exist.

      In the next step, we'll create corresponding URL routes to match the views we've created.

      Step 3 — Mapping URLs to Views

      Django makes it possible to create URLs that connect to views with a Python module called a URLconf. This module maps URL path expressions to Python functions (your views). Usually, a URL configuration file is auto-generated when you create a project. In this step, you will update this file to include new routes for the views you created in the previous step, along with the URLs for the django-webpush app, which will provide endpoints to subscribe users to push notifications.

      For more information about views, please see How To Create Django Views.

      Open urls.py:

      • nano ~/djangopush/djangopush/urls.py

      The file will look like this:

      ~/djangopush/djangopush/urls.py

      
      """untitled URL Configuration
      
      The `urlpatterns` list routes URLs to views. For more information please see:
          https://docs.djangoproject.com/en/2.1/topics/http/urls/
      Examples:
      Function views
          1. Add an import:  from my_app import views
          2. Add a URL to urlpatterns:  path('', views.home, name='home')
      Class-based views
          1. Add an import:  from other_app.views import Home
          2. Add a URL to urlpatterns:  path('', Home.as_view(), name='home')
      Including another URLconf
          1. Import the include() function: from django.urls import include, path
          2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
      """
      from django.contrib import admin
      from django.urls import path
      
      urlpatterns = [
          path('admin/', admin.site.urls),
      ]
      

      The next step is to map the views you've created to URLs. First, add the include import to ensure that all of the routes for the Django-Webpush library will be added to your project:

      ~/djangopush/djangopush/urls.py

      
      """webpushdjango URL Configuration
      ...
      """
      from django.contrib import admin
      from django.urls import path, include
      

      Next, import the views you created in the last step and update the urlpatterns list to map your views:

      ~/djangopush/djangopush/urls.py

      
      """webpushdjango URL Configuration
      ...
      """
      from django.contrib import admin
      from django.urls import path, include
      
      from .views import home, send_push
      
      urlpatterns = [
                        path('admin/', admin.site.urls),
                        path('', home),
                        path('send_push', send_push),
                        path('webpush/', include('webpush.urls')),
                    ]
      

      Here, the urlpatterns list registers the URLs for the django-webpush package and maps your views to the URLs /send_push and /home.

      Let's test the /home view to be sure that it's working as intended. Make sure you're in the root directory of the project:

      Start your server by running the following command:

      • python manage.py runserver your_server_ip:8000

      Navigate to http://your_server_ip:8000. You should see the following home page:

      Initial Home Page view

      At this point, you can kill the server with CTRL+C, and we will move on to creating templates and rendering them in our views using the render function.

      Step 4 — Creating Templates

      Django’s template engine allows you to define the user-facing layers of your application with templates, which are similar to HTML files. In this step, you will create and render a template for the home view.

      Create a folder called templates in your project's root directory:

      • mkdir ~/djangopush/templates

      If you run ls in the root folder of your project at this point, the output will look like this:

      Output

      /djangopush /templates db.sqlite3 manage.py /my_env

      Create a file called home.html in the templates folder:

      • nano ~/djangopush/templates/home.html

      Add the following code to the file to create a form where users can enter information to create push notifications:

      {% load static %}
      <!DOCTYPE html>
      <html lang="en">
      <head>
          <meta charset="UTF-8">
          <meta name="viewport" content="width=device-width, initial-scale=1.0">
          <meta http-equiv="X-UA-Compatible" content="ie=edge">
          <meta name="vapid-key" content="{{ vapid_key }}">
          {% if user.id %}
              <meta name="user_id" content="{{ user.id }}">
          {% endif %}
          <title>Web Push</title>
          <link href="https://fonts.googleapis.com/css?family=PT+Sans:400,700" rel="stylesheet">
      </head>
      
      <body>
      <div>
          <form id="send-push__form">
              <h3 class="header">Send a push notification</h3>
              <p class="error"></p>
              <input type="text" name="head" placeholder="Header: Your favorite airline 😍">
              <textarea name="body" id="" cols="30" rows="10" placeholder="Body: Your flight has been cancelled 😱😱😱"></textarea>
              <button>Send Me</button>
          </form>
      </div>
      </body>
      </html>
      

      The body of the file includes a form with two fields: an input element will hold the head/title of the notification and a textarea element will hold the notification body.

      In the head section of the file, there are two meta tags that will hold the VAPID public key and the user's id. These two variables are required to register a user and send them push notifications. The user's id is required here because you'll be sending AJAX requests to the server and the id will be used to identify the user. If the current user is a registered user, then the template will create a meta tag with their id as the content.

      The next step is to tell Django where to find your templates. To do this, you will edit settings.py and update the TEMPLATES list.

      Open the settings.py file:

      • nano ~/djangopush/djangopush/settings.py

      Add the following to the DIRS list to specify the path to the templates directory:

      ~/djangopush/djangopush/settings.py

      ...
      TEMPLATES = [
          {
              'BACKEND': 'django.template.backends.django.DjangoTemplates',
              'DIRS': [os.path.join(BASE_DIR, 'templates')],
              'APP_DIRS': True,
              'OPTIONS': {
                  'context_processors': [
                      ...
                  ],
              },
          },
      ]
      ...
      

      Next, in your views.py file, update the home view to render the home.html template. Open the file:

      • nano ~/djangpush/djangopush/views.py

      First, add some additional imports, including the settings configuration, which contains all of the project's settings from the settings.py file, and the render function from django.shortcuts:

      ~/djangopush/djangopush/views.py

      ...
      from django.shortcuts import render, get_object_or_404
      ...
      import json
      from django.conf import settings
      
      ...
      

      Next, remove the initial code you added to the home view and add the following, which specifies how the template you just created will be rendered:

      ~/djangopush/djangopush/views.py

      ...
      
      @require_GET
      def home(request):
         webpush_settings = getattr(settings, 'WEBPUSH_SETTINGS', {})
         vapid_key = webpush_settings.get('VAPID_PUBLIC_KEY')
         user = request.user
         return render(request, 'home.html', {user: user, 'vapid_key': vapid_key})
      

      The code assigns the following variables:

      • webpush_settings: This is assigned the value of the WEBPUSH_SETTINGS attribute from the settings configuration.
      • vapid_key: This gets the VAPID_PUBLIC_KEY value from the webpush_settings object to send to the client. This public key is checked against the private key to ensure that the client with the public key is permitted to receive push messages from the server.
      • user: This variable comes from the incoming request. Whenever a user makes a request to the server, the details for that user are stored in the user field.

      The render function will return an HTML file and a context object containing the current user and the server's vapid public key. It takes three parameters here: the request, the template to be rendered, and the object that contains the variables that will be used in the template.

      With our template created and the home view updated, we can move on to configuring Django to serve our static files.

      Step 5 — Serving Static Files

      Web applications include CSS, JavaScript, and other image files that Django refers to as “static files”. Django allows you to collect all of the static files from each application in your project into a single location from which they are served. This solution is called django.contrib.staticfiles. In this step, we'll update our settings to tell Django where our static files will be stored.

      Open settings.py:

      • nano ~/djangopush/djangopush/settings.py

      In settings.py, first ensure that the STATIC_URL has been defined:

      ~/djangopush/djangopush/settings.py

      ...
      STATIC_URL = '/static/'
      

      Next, add a list of directories called STATICFILES_DIRS where Django will look for static files:

      ~/djangopush/djangopush/settings.py

      ...
      STATIC_URL = '/static/'
      STATICFILES_DIRS = [
          os.path.join(BASE_DIR, "static"),
      ]
      

      You can now add the STATIC_URL to the list of paths defined in your urls.py file.

      Open the file:

      • nano ~/djangopush/djangopush/urls.py

      Add the following code, which will import the static url configuration and update the urlpatterns list. The helper function here uses the STATIC_URL and STATIC_ROOT properties we provided in the settings.py file to serve the project's static files:

      ~/djangopush/djangopush/urls.py

      
      ...
      from django.conf import settings
      from django.conf.urls.static import static
      
      urlpatterns = [
          ...
      ]  + static(settings.STATIC_URL, document_root=settings.STATIC_ROOT)
      

      With our static files settings configured, we can move on to styling the application's home page.

      Step 6 — Styling the Home Page

      After setting up your application to serve static files, you can create an external stylesheet and link it to the home.html file to style the home page. All of your static files will be stored in a static directory in the root folder of your project.

      Create a static folder and a css folder within the static folder:

      • mkdir -p ~/djangopush/static/css

      Open a css file called styles.css inside the css folder:

      • nano ~/djangopush/static/css/styles.css

      Add the following styles for the home page:

      ~/djangopush/static/css/styles.css

      
      body {
          height: 100%;
          background: rgba(0, 0, 0, 0.87);
          font-family: 'PT Sans', sans-serif;
      }
      
      div {
          height: 100%;
          display: flex;
          align-items: center;
          justify-content: center;
      }
      
      form {
          display: flex;
          flex-direction: column;
          align-items: center;
          justify-content: center;
          width: 35%;
          margin: 10% auto;
      }
      
      form > h3 {
          font-size: 17px;
          font-weight: bold;
          margin: 15px 0;
          color: orangered;
          text-transform: uppercase;
      }
      
      form > .error {
          margin: 0;
          font-size: 15px;
          font-weight: normal;
          color: orange;
          opacity: 0.7;
      }
      
      form > input, form > textarea {
          border: 3px solid orangered;
          box-shadow: unset;
          padding: 13px 12px;
          margin: 12px auto;
          width: 80%;
          font-size: 13px;
          font-weight: 500;
      }
      
      form > input:focus, form > textarea:focus {
          border: 3px solid orangered;
          box-shadow: 0 2px 3px 0 rgba(0, 0, 0, 0.2);
          outline: unset;
      }
      
      form > button {
          justify-self: center;
          padding: 12px 25px;
          border-radius: 0;
          text-transform: uppercase;
          font-weight: 600;
          background: orangered;
          color: white;
          border: none;
          font-size: 14px;
          letter-spacing: -0.1px;
          cursor: pointer;
      }
      
      form > button:disabled {
          background: dimgrey;
          cursor: not-allowed;
      }
      

      With the stylesheet created, you can link it to the home.html file using static template tags. Open the home.html file:

      • nano ~/djangopush/templates/home.html

      Update the head section to include a link to the external stylesheet:

      ~/djangopush/templates/home.html

      
      {% load static %}
      <!DOCTYPE html>
      <html lang="en">
      
      <head>
          ...
          <link href="http://www.digitalocean.com/{% static"/css/styles.css' %}" rel="stylesheet">
      </head>
      <body>
          ...
      </body>
      </html>
      

      Make sure that you are in your main project directory and start your server again to inspect your work:

      • cd ~/djangopush
      • python manage.py runserver your_server_ip:8000

      When you visit http://your_server_ip:8000, it should look like this:

      Home page view
      Again, you can kill the server with CTRL+C.

      Now that you have successfully created the home.html page and styled it, you can subscribe users to push notifications whenever they visit the home page.

      Step 7 — Registering a Service Worker and Subscribing Users to Push Notifications

      Web push notifications can notify users when there are updates to applications they are subscribed to or prompt them to re-engage with applications they have used in the past. They rely on two technologies, the push API and the notifications API. Both technologies rely on the presence of a service worker.

      A push is invoked when the server provides information to the service worker and the service worker uses the notifications API to display this information.

      We'll subscribe our users to the push and then we'll send the information from the subscription to the server to register them.

      In the static directory, create a folder called js:

      • mkdir ~/djangopush/static/js

      Create a file called registerSw.js:

      • nano ~/djangopush/static/js/registerSw.js

      Add the following code, which checks if service workers are supported on the user's browser before attempting to register a service worker:

      ~/djangopush/static/js/registerSw.js

      
      const registerSw = async () => {
          if ('serviceWorker' in navigator) {
              const reg = await navigator.serviceWorker.register('sw.js');
              initialiseState(reg)
      
          } else {
              showNotAllowed("You can't send push notifications ☹️😢")
          }
      };
      

      First, the registerSw function checks if the browser supports service workers before registering them. After registration, it calls the initializeState function with the registration data. If service workers are not supported in the browser, it calls the showNotAllowed function.

      Next, add the following code below the registerSw function to check if a user is eligible to receive push notifications before attempting to subscribe them:

      ~/djangopush/static/js/registerSw.js

      
      ...
      
      const initialiseState = (reg) => {
          if (!reg.showNotification) {
              showNotAllowed('Showing notifications isn't supported ☹️😢');
              return
          }
          if (Notification.permission === 'denied') {
              showNotAllowed('You prevented us from showing notifications ☹️🤔');
              return
          }
          if (!'PushManager' in window) {
              showNotAllowed("Push isn't allowed in your browser 🤔");
              return
          }
          subscribe(reg);
      }
      
      const showNotAllowed = (message) => {
          const button = document.querySelector('form>button');
          button.innerHTML = `${message}`;
          button.setAttribute('disabled', 'true');
      };
      

      The initializeState function checks the following:

      • Whether or not the user has enabled notifications, using the value of reg.showNotification.
      • Whether or not the user has granted the application permission to display notifications.
      • Whether or not the browser supports the PushManager API.
        If any of these checks fail, the showNotAllowed function is called and the subscription is aborted.

      The showNotAllowed function displays a message on the button and disables it if a user is ineligible to receive notifications. It also displays appropriate messages if a user has restricted the application from displaying notifications or if the browser doesn't support push notifications.

      Once we ensure that a user is eligible to receive push notifications, the next step is to subscribe them using pushManager. Add the following code below the showNotAllowed function:

      ~/djangopush/static/js/registerSw.js

      
      ...
      
      function urlB64ToUint8Array(base64String) {
          const padding = '='.repeat((4 - base64String.length % 4) % 4);
          const base64 = (base64String + padding)
              .replace(/-/g, '+')
              .replace(/_/g, '/');
      
          const rawData = window.atob(base64);
          const outputArray = new Uint8Array(rawData.length);
          const outputData = outputArray.map((output, index) => rawData.charCodeAt(index));
      
          return outputData;
      }
      
      const subscribe = async (reg) => {
          const subscription = await reg.pushManager.getSubscription();
          if (subscription) {
              sendSubData(subscription);
              return;
          }
      
          const vapidMeta = document.querySelector('meta[name="vapid-key"]');
          const key = vapidMeta.content;
          const options = {
              userVisibleOnly: true,
              // if key exists, create applicationServerKey property
              ...(key && {applicationServerKey: urlB64ToUint8Array(key)})
          };
      
          const sub = await reg.pushManager.subscribe(options);
          sendSubData(sub)
      };
      

      Calling the pushManager.getSubscription function returns the data for an active subscription. When an active subscription exists, the sendSubData function is called with the subscription info passed in as a parameter.

      When no active subscription exists, the VAPID public key, which is Base64 URL-safe encoded, is converted to a Uint8Array using the urlB64ToUint8Array function. pushManager.subscribe is then called with the VAPID public key and the userVisible value as options. You can read more about the available options here.

      After successfully subscribing a user, the next step is to send the subscription data to the server. The data will be sent to the webpush/save_information endpoint provided by the django-webpush package. Add the following code below the subscribe function:

      ~/djangopush/static/js/registerSw.js

      
      ...
      
      const sendSubData = async (subscription) => {
          const browser = navigator.userAgent.match(/(firefox|msie|chrome|safari|trident)/ig)[0].toLowerCase();
          const data = {
              status_type: 'subscribe',
              subscription: subscription.toJSON(),
              browser: browser,
          };
      
          const res = await fetch('/webpush/save_information', {
              method: 'POST',
              body: JSON.stringify(data),
              headers: {
                  'content-type': 'application/json'
              },
              credentials: "include"
          });
      
          handleResponse(res);
      };
      
      const handleResponse = (res) => {
          console.log(res.status);
      };
      
      registerSw();
      

      The save_information endpoint requires information about the status of the subscription (subscribe and unsubscribe), the subscription data, and the browser. Finally, we call the registerSw() function to begin the process of subscribing the user.

      The completed file looks like this:

      ~/djangopush/static/js/registerSw.js

      
      const registerSw = async () => {
          if ('serviceWorker' in navigator) {
              const reg = await navigator.serviceWorker.register('sw.js');
              initialiseState(reg)
      
          } else {
              showNotAllowed("You can't send push notifications ☹️😢")
          }
      };
      
      const initialiseState = (reg) => {
          if (!reg.showNotification) {
              showNotAllowed('Showing notifications isn't supported ☹️😢');
              return
          }
          if (Notification.permission === 'denied') {
              showNotAllowed('You prevented us from showing notifications ☹️🤔');
              return
          }
          if (!'PushManager' in window) {
              showNotAllowed("Push isn't allowed in your browser 🤔");
              return
          }
          subscribe(reg);
      }
      
      const showNotAllowed = (message) => {
          const button = document.querySelector('form>button');
          button.innerHTML = `${message}`;
          button.setAttribute('disabled', 'true');
      };
      
      function urlB64ToUint8Array(base64String) {
          const padding = '='.repeat((4 - base64String.length % 4) % 4);
          const base64 = (base64String + padding)
              .replace(/-/g, '+')
              .replace(/_/g, '/');
      
          const rawData = window.atob(base64);
          const outputArray = new Uint8Array(rawData.length);
          const outputData = outputArray.map((output, index) => rawData.charCodeAt(index));
      
          return outputData;
      }
      
      const subscribe = async (reg) => {
          const subscription = await reg.pushManager.getSubscription();
          if (subscription) {
              sendSubData(subscription);
              return;
          }
      
          const vapidMeta = document.querySelector('meta[name="vapid-key"]');
          const key = vapidMeta.content;
          const options = {
              userVisibleOnly: true,
              // if key exists, create applicationServerKey property
              ...(key && {applicationServerKey: urlB64ToUint8Array(key)})
          };
      
          const sub = await reg.pushManager.subscribe(options);
          sendSubData(sub)
      };
      
      const sendSubData = async (subscription) => {
          const browser = navigator.userAgent.match(/(firefox|msie|chrome|safari|trident)/ig)[0].toLowerCase();
          const data = {
              status_type: 'subscribe',
              subscription: subscription.toJSON(),
              browser: browser,
          };
      
          const res = await fetch('/webpush/save_information', {
              method: 'POST',
              body: JSON.stringify(data),
              headers: {
                  'content-type': 'application/json'
              },
              credentials: "include"
          });
      
          handleResponse(res);
      };
      
      const handleResponse = (res) => {
          console.log(res.status);
      };
      
      registerSw();
      

      Next, add a script tag for the registerSw.js file in home.html. Open the file:

      • nano ~/djangopush/templates/home.html

      Add the script tag before the closing tag of the body element:

      ~/djangopush/templates/home.html

      
      {% load static %}
      <!DOCTYPE html>
      <html lang="en">
      
      <head>
         ...
      </head>
      <body>
         ...
         <script src="https://www.digitalocean.com/{% static"/js/registerSw.js' %}"></script>
      </body>
      </html>
      

      Because a service worker doesn't yet exist, if you left your application running or tried to start it again, you would see an error message. Let's fix this by creating a service worker.

      Step 8 — Creating a Service Worker

      To display a push notification, you'll need an active service worker installed on your application's home page. We'll create a service worker that listens for push events and displays the messages when ready.

      Because we want the scope of the service worker to be the entire domain, we will need to install it in the application's root. You can read more about the process in this article outlining how to register a service worker. Our approach will be to create a sw.js file in the templates folder, which we will then register as a view.

      Create the file:

      • nano ~/djangopush/templates/sw.js

      Add the following code, which tells the service worker to listen for push events:

      ~/djangopush/templates/sw.js

      
      // Register event listener for the 'push' event.
      self.addEventListener('push', function (event) {
          // Retrieve the textual payload from event.data (a PushMessageData object).
          // Other formats are supported (ArrayBuffer, Blob, JSON), check out the documentation
          // on https://developer.mozilla.org/en-US/docs/Web/API/PushMessageData.
          const eventInfo = event.data.text();
          const data = JSON.parse(eventInfo);
          const head = data.head || 'New Notification 🕺🕺';
          const body = data.body || 'This is default content. Your notification didn't have one 🙄🙄';
      
          // Keep the service worker alive until the notification is created.
          event.waitUntil(
              self.registration.showNotification(head, {
                  body: body,
                  icon: 'https://i.imgur.com/MZM3K5w.png'
              })
          );
      });
      

      The service worker listens for a push event. In the callback function, the event data is converted to text. We use default title and body strings if the event data doesn't have them. The showNotification function takes the notification title, the header of the notification to be displayed, and an options object as parameters. The options object contains several properties to configure the visual options of a notification.

      For your service worker to work for the entirety of your domain, you will need to install it in the root of the application. We'll use TemplateView to allow the service worker access to the whole domain.

      Open the urls.py file:

      • nano ~/djangopush/djangopush/urls.py

      Add a new import statement and path in the urlpatterns list to create a class-based view:

      ~/djangopush/djangopush/urls.py

      ...
      from django.views.generic import TemplateView
      
      urlpatterns = [
                        ...,
                        path('sw.js', TemplateView.as_view(template_name='sw.js', content_type='application/x-javascript'))
                    ] + static(settings.STATIC_URL, document_root=settings.STATIC_ROOT)
      

      Class-based views like TemplateView allow you to create flexible, reusable views. In this case, the TemplateView.as_view method creates a path for the service worker by passing the recently created service worker as a template and application/x-javascript as the content_type of the template.

      You have now created a service worker and registered it as a route. Next, you'll set up the form on the home page to send push notifications.

      Step 9 — Sending Push Notifications

      Using the form on the home page, users should be able to send push notifications while your server is running. You can also send push notifications using any RESTful service like Postman. When the user sends push notifications from the form on the home page, the data will include a head and body, as well as the id of the receiving user. The data should be structured in the following manner:

      {
          head: "Title of the notification",
          body: "Notification body",
          id: "User's id"
      }
      

      To listen for the submit event of the form and send the data entered by the user to the server, we will create a file called site.js in the ~/djangopush/static/js directory.

      Open the file:

      • nano ~/djangopush/static/js/site.js

      First, add a submit event listener to the form that will enable you to get the values of the form inputs and the user id stored in the meta tag of your template:

      ~/djangopush/static/js/site.js

      
      const pushForm = document.getElementById('send-push__form');
      const errorMsg = document.querySelector('.error');
      
      pushForm.addEventListener('submit', async function (e) {
          e.preventDefault();
          const input = this[0];
          const textarea = this[1];
          const button = this[2];
          errorMsg.innerText = '';
      
          const head = input.value;
          const body = textarea.value;
          const meta = document.querySelector('meta[name="user_id"]');
          const id = meta ? meta.content : null;
          ...
          // TODO: make an AJAX request to send notification
      });
      

      The pushForm function gets the input, textarea, and button inside the form. It also gets the information from the meta tag, including the name attribute user_id and the user's id stored in the content attribute of the tag. With this information, it can send a POST request to the /send_push endpoint on the server.

      To send requests to the server, we'll use the native Fetch API. We're using Fetch here because it is supported by most browsers and doesn't require external libraries to function. Below the code you've added, update the pushForm function to include the code for sending AJAX requests:

      ~/djangopush/static/js/site.js

      const pushForm = document.getElementById('send-push__form');
      const errorMsg = document.querySelector('.error');
      
      pushForm.addEventListener('submit', async function (e) {
           ...
          const id = meta ? meta.content : null;
      
           if (head && body && id) {
              button.innerText = 'Sending...';
              button.disabled = true;
      
              const res = await fetch('/send_push', {
                  method: 'POST',
                  body: JSON.stringify({head, body, id}),
                  headers: {
                      'content-type': 'application/json'
                  }
              });
              if (res.status === 200) {
                  button.innerText = 'Send another 😃!';
                  button.disabled = false;
                  input.value = '';
                  textarea.value = '';
              } else {
                  errorMsg.innerText = res.message;
                  button.innerText = 'Something broke 😢..  Try again?';
                  button.disabled = false;
              }
          }
          else {
              let error;
              if (!head || !body){
                  error = 'Please ensure you complete the form 🙏🏾'
              }
              else if (!id){
                  error = "Are you sure you're logged in? 🤔. Make sure! 👍🏼"
              }
              errorMsg.innerText = error;
          }
      });
      

      If the three required parameters head, body, and id are present, we send the request and disable the submit button temporarily.

      The completed file looks like this:

      ~/djangopush/static/js/site.js

      const pushForm = document.getElementById('send-push__form');
      const errorMsg = document.querySelector('.error');
      
      pushForm.addEventListener('submit', async function (e) {
          e.preventDefault();
          const input = this[0];
          const textarea = this[1];
          const button = this[2];
          errorMsg.innerText = '';
      
          const head = input.value;
          const body = textarea.value;
          const meta = document.querySelector('meta[name="user_id"]');
          const id = meta ? meta.content : null;
      
          if (head && body && id) {
              button.innerText = 'Sending...';
              button.disabled = true;
      
              const res = await fetch('/send_push', {
                  method: 'POST',
                  body: JSON.stringify({head, body, id}),
                  headers: {
                      'content-type': 'application/json'
                  }
              });
              if (res.status === 200) {
                  button.innerText = 'Send another 😃!';
                  button.disabled = false;
                  input.value = '';
                  textarea.value = '';
              } else {
                  errorMsg.innerText = res.message;
                  button.innerText = 'Something broke 😢..  Try again?';
                  button.disabled = false;
              }
          }
          else {
              let error;
              if (!head || !body){
                  error = 'Please ensure you complete the form 🙏🏾'
              }
              else if (!id){
                  error = "Are you sure you're logged in? 🤔. Make sure! 👍🏼"
              }
              errorMsg.innerText = error;
          }    
      });
      

      Finally, add the site.js file to home.html:

      • nano ~/djangopush/templates/home.html

      Add the script tag:

      ~/djangopush/templates/home.html

      
      {% load static %}
      <!DOCTYPE html>
      <html lang="en">
      
      <head>
         ...
      </head>
      <body>
         ...
         <script src="https://www.digitalocean.com/{% static"/js/site.js' %}"></script>
      </body>
      </html>
      

      At this point, if you left your application running or tried to start it again, you would see an error, since service workers can only function in secure domains or on localhost. In the next step we'll use ngrok to create a secure tunnel to our web server.

      Step 10 — Creating a Secure Tunnel to Test the Application

      Service workers require secure connections to function on any site except localhost since they can allow connections to be hijacked and responses to be filtered and fabricated. For this reason, we'll create a secure tunnel for our server with ngrok.

      Open a second terminal window and ensure you're in your home directory:

      If you started with a clean 18.04 server in the prerequisites, then you will need to install unzip:

      • sudo apt update && sudo apt install unzip

      Download ngrok:

      • wget https://bin.equinox.io/c/4VmDzA7iaHb/ngrok-stable-linux-amd64.zip
      • unzip ngrok-stable-linux-amd64.zip

      Move ngrok to /usr/local/bin, so that you will have access to the ngrok command from the terminal:

      • sudo mv ngrok /usr/local/bin

      In your first terminal window, make sure that you are in your project directory and start your server:

      • cd ~/djangopush
      • python manage.py runserver your_server_ip:8000

      You will need to do this before creating a secure tunnel for your application.

      In your second terminal window, navigate to your project folder, and activate your virtual environment:

      • cd ~/djangopush
      • source my_env/bin/activate

      Create the secure tunnel to your application:

      • ngrok http your_server_ip:8000

      You will see the following output, which includes information about your secure ngrok URL:

      Output

      ngrok by @inconshreveable (Ctrl+C to quit) Session Status online Session Expires 7 hours, 59 minutes Version 2.2.8 Region United States (us) Web Interface http://127.0.0.1:4040 Forwarding http://ngrok_secure_url -> 203.0.113.0:8000 Forwarding https://ngrok_secure_url -> 203.0.113.0:8000 Connections ttl opn rt1 rt5 p50 p90 0 0 0.00 0.00 0.00 0.00

      Copy the ngrok_secure_url from the console output. You will need to add it to the list of ALLOWED_HOSTS in your settings.py file.

      Open another terminal window, navigate to your project folder, and activate your virtual environment:

      • cd ~/djangopush
      • source my_env/bin/activate

      Open the settings.py file:

      • nano ~/djangopush/djangopush/settings.py

      Update the list of ALLOWED_HOSTS with the ngrok secure tunnel:

      ~/djangopush/djangopush/settings.py

      ...
      
      ALLOWED_HOSTS = ['your_server_ip', 'ngrok_secure_url']
      ...
      
      

      Navigate to the secure admin page to log in: https://ngrok_secure_url/admin/. You will see a screen that looks like this:

      ngrok admin login

      Enter your Django admin user information on this screen. This should be the same information you entered when you logged into the admin interface in the prerequisite steps. You are now ready to send push notifications.

      Visit https://ngrok_secure_url in your browser. You will see a prompt asking for permission to display notifications. Click the Allow button to let your browser display push notifications:

      push notifications request

      Submitting a filled form will display a notification similar to this:

      screenshot of notification

      Note: Be sure that your server is running before attempting to send notifications.

      If you received notifications then your application is working as expected.

      You have created a web application that triggers push notifications on the server and, with the help of service workers, receives and displays notifications. You also went through the steps of obtaining the VAPID keys that are required to send push notifications from an application server.

      Conclusion

      In this tutorial, you've learned how to subscribe users to push notifications, install service workers, and display push notifications using the notifications API.

      You can go even further by configuring the notifications to open specific areas of your application when clicked. The source code for this tutorial can be found here.



      Source link

      How To Build a Modern Web Application to Manage Customer Information with Django and React on Ubuntu 18.04


      The author selected Open Sourcing Mental Illness Ltd to receive a donation as part of the Write for DOnations program.

      Introduction

      People use different types of devices to connect to the internet and browse the Web. Because of this, applications need to be accessible from a variety of locations. For traditional websites, having a responsive UI is usually enough, but more complex applications often require the use of other techniques and architectures. These include having separate REST back-end and front-end applications that can be implemented as client-side web applications, Progressive Web Apps (PWAs), or native mobile apps.

      Some tools that you can use when building more complex applications include:

      • React, a JavaScript framework that allows developers to build web and native frontends for their REST API backends.
      • Django, a free and open-source Python web framework that follows the model view controller (MVC) software architectural pattern.
      • Django REST framework, a powerful and flexible toolkit for building REST APIs in Django.

      In this tutorial, you will build a modern web application with a separate REST API backend and frontend using React, Django, and the Django REST Framework. By using React with Django, you’ll be able to benefit from the latest advancements in JavaScript and front-end development. Instead of building a Django application that uses a built-in template engine, you will use React as a UI library, taking advantage of its virtual Document Object Model (DOM), declarative approach, and components that quickly render changes in data.

      The web application you will build stores records about customers in a database, and you can use it as a starting point for a CRM application. When you are finished you’ll be able to create, read, update, and delete records using a React interface styled with Bootstrap 4.

      Prerequisites

      To complete this tutorial, you will need:

      Step 1 — Creating a Python Virtual Environment and Installing Dependencies

      In this step, we’ll create a virtual environment and install the required dependencies for our application, including Django, the Django REST framework, and django-cors-headers.

      Our application will use two different development servers for Django and React. They will run on different ports and will function as two separate domains. Because of this, we need to enable cross-origin resource sharing (CORS) to send HTTP requests from React to Django without being blocked by the browser.

      Navigate to your home directory and create a virtual environment using the venv Python 3 module:

      • cd ~
      • python3 -m venv ./env

      Activate the created virtual environment using source:

      Next, install the project's dependencies with pip. These will include:

      • Django: The web framework for the project.
      • Django REST framework: A third-party application that builds REST APIs with Django.
      • django-cors-headers: A package that enables CORS.

      Install the Django framework:

      • pip install django djangorestframework django-cors-headers

      With the project dependencies installed, you can create the Django project and the React frontend.

      Step 2 — Creating the Django Project

      In this step, we'll generate the Django project using the following commands and utilities:

      • django-admin startproject project-name: django-admin is a command-line utility used to accomplish tasks with Django. The startproject command creates a new Django project.

      • python manage.py startapp myapp: manage.py is a utility script, automatically added to each Django project, that performs a number of administrative tasks: creating new applications, migrating the database, and serving the Django project locally. Its startapp command creates a Django application inside the Django project. In Django, the term application describes a Python package that provides some set of features in a project.

      To begin, create the Django project with django-admin startproject. We will call our project djangoreactproject:

      • django-admin startproject djangoreactproject

      Before moving on, let's look at the directory structure of our Django project using the tree command.

      Tip: tree is a useful command for viewing file and directory structures from the command line. You can install it with the following command:

      • sudo apt-get install tree

      To use it, cd into the directory you want and type tree or provide the path to the starting point with tree /home/sammy/sammys-project.

      Navigate to the djangoreactproject folder within your project root and run the tree command:

      • cd ~/djangoreactproject
      • tree

      You will see the following output:

      Output

      ├── djangoreactproject │ ├── __init__.py │ ├── settings.py │ ├── urls.py │ └── wsgi.py └── manage.py

      The ~/djangoreactproject folder is the root of the project. Within this folder, there are several files that will be important to your work:

      • manage.py: The utility script that does a number of administrative tasks.
      • settings.py: The main configuration file for the Django project where you can modify the project's settings. These settings include variables such as INSTALLED_APPS, a list of strings designating the enabled applications for your project. The Django documentation has more information about available settings.
      • urls.py: This file contains a list of URL patterns and related views. Each pattern maps a connection between a URL and the function that should be called for that URL. For more on URLs and views, please refer to our tutorial on How To Create Django Views.

      Our first step in working with the project will be to configure the packages we installed in the previous step, including the Django REST framework and the Django CORS package, by adding them to settings.py. Open the file with nano or your favorite editor:

      • nano ~/djangoreactproject/djangoreactproject/settings.py

      Navigate to the INSTALLED_APPS setting and add the rest_framework and corsheaders applications to the bottom of the list:

      ~/djangoreactproject/djangoreactproject/settings.py

      ...
      INSTALLED_APPS = [
          'django.contrib.admin',
          'django.contrib.auth',
          'django.contrib.contenttypes',
          'django.contrib.sessions',
          'django.contrib.messages',
          'django.contrib.staticfiles',
          'rest_framework',
          'corsheaders'
      ]
      

      Next, add the corsheaders.middleware.CorsMiddleware middleware from the previously installed CORS package to the MIDDLEWARE setting. This setting is a list of middlewares, a Python class that contains code processed each time your web application handles a request or response:

      ~/djangoreactproject/djangoreactproject/settings.py

      ...
      
      MIDDLEWARE = [
      ...
      'django.contrib.messages.middleware.MessageMiddleware',
      'django.middleware.clickjacking.XFrameOptionsMiddleware',
      'corsheaders.middleware.CorsMiddleware'
      ]
      

      Next, you can enable CORS. The CORS_ORIGIN_ALLOW_ALL setting specifies whether or not you want to allow CORS for all domains, and CORS_ORIGIN_WHITELIST is a Python tuple that contains allowed URLs. In our case, because the React development server will be running at http://localhost:3000, we will add new CORS_ORIGIN_ALLOW_ALL = False and CORS_ORIGIN_WHITELIST('localhost:3000',) settings to our settings.py file. Add these settings anywhere in the file:

      ~/djangoreactproject/djangoreactproject/settings.py

      
      ...
      CORS_ORIGIN_ALLOW_ALL = False
      
      CORS_ORIGIN_WHITELIST = (
             'localhost:3000',
      )
      ...
      

      You can find more configuration options in the django-cors-headers docs.

      Save the file and exit the editor when you are finished.

      Still in the ~/djangoreactproject directory, make a new Django application called customers:

      • python manage.py startapp customers

      This will contain the models and views for managing customers. Models define the fields and behaviors of our application data, while views enable our application to properly handle web requests and return the required responses.

      Next, add this application to the list of installed applications in your project's settings.py file so Django will recognize it as part of the project. Open settings.py again:

      • nano ~/djangoreactproject/djangoreactproject/settings.py

      Add the customers application:

      ~/djangoreactproject/djangoreactproject/settings.py

      ...
      INSTALLED_APPS = [
          ...
          'rest_framework',
          'corsheaders',
          'customers'
      ]
      ...
      

      Next, migrate the database and start the local development server. Migrations are Django’s way of propagating the changes you make to your models into your database schema. These changes can include things like adding a field or deleting a model, for example. For more on models and migrations, see How To Create Django Models.

      Migrate the database:

      Start the local development server:

      • python manage.py runserver

      You will see output similar to the following:

      Output

      Performing system checks... System check identified no issues (0 silenced). October 22, 2018 - 15:14:50 Django version 2.1.2, using settings 'djangoreactproject.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CONTROL-C.

      Your web application will be running from http://127.0.0.1:8000. If you navigate to this address in your web browser you should see the following page:

      Django demo page

      At this point, leave the application running and open a new terminal to continue developing the project.

      Step 3 — Creating the React Frontend

      In this section, we're going to create the front-end application of our project using React.

      React has an official utility that allows you to quickly generate React projects without having to configure Webpack directly. Webpack is a module bundler used to bundle web assets such as JavaScript code, CSS, and images. Typically, before you can use Webpack you need to set various configuration options, but thanks to the create-react-app utility you don't have to deal with Webpack directly until you decide you need more control. To run create-react-app you can use npx, a tool that executes npm package binaries.

      In your second terminal, make sure you are in your project directory:

      Create a React project called frontend using create-react-app and npx:

      • npx create-react-app frontend

      Next, navigate inside your React application and start the development server:

      • cd ~/djangoreactproject/frontend
      • npm start

      You application will be running from http://localhost:3000/:

      React demo page

      Leave the React development server running and open another terminal window to proceed.

      To see the directory structure of the entire project at this point, navigate to the root folder and run tree again:

      • cd ~/djangoreactproject
      • tree

      You'll see a structure like this:

      Output

      ├── customers │ ├── admin.py │ ├── apps.py │ ├── __init__.py │ ├── migrations │ │ └── __init__.py │ ├── models.py │ ├── tests.py │ └── views.py ├── djangoreactproject │ ├── __init__.py │ ├── __pycache__ │ ├── settings.py │ ├── urls.py │ └── wsgi.py ├── frontend │ ├── package.json │ ├── public │ │ ├── favicon.ico │ │ ├── index.html │ │ └── manifest.json │ ├── README.md │ ├── src │ │ ├── App.css │ │ ├── App.js │ │ ├── App.test.js │ │ ├── index.css │ │ ├── index.js │ │ ├── logo.svg │ │ └── registerServiceWorker.js │ └── yarn.lock └── manage.py

      Our application will use Bootstrap 4 to style the React interface, so we will include it in the frontend/src/App.css file, which manages our CSS settings. Open the file:

      • nano ~/djangoreactproject/frontend/src/App.css

      Add the following import to the beginning of the file. You can delete the file's existing content, though that's not required:

      ~/djangoreactproject/frontend/src/App.css

      @import  'https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css';
      

      Here, @import is a CSS instruction that's used to import style rules from other style sheets.

      Now that we have created both the back-end and front-end applications, let's create the Customer model and some demo data.

      Step 4 — Creating the Customer Model and Initial Data

      After creating the Django application and the React frontend, our next step will be to create the Customer model, which represents the database table that will hold information about customers. You don't need any SQL since the Django Object Relational Mapper (ORM) will handle database operations by mapping Python classes and variables to SQL tables and columns. In this way the Django ORM abstracts SQL interactions with the database through a Python interface.

      Activate your virtual environment again:

      • cd ~
      • source env/bin/activate

      Move to the customers directory, and open models.py, a Python file that holds the models of your application:

      • cd ~/djangoreactproject/customers/
      • nano models.py

      The file will contain the following content:

      ~/djangoreactproject/customers/models.py

      from django.db import models
      # Create your models here.
      

      The Customer model's API is already imported in the file thanks to the from django.db import models import statement. You will now add the Customer class, which extends models.Model. Each model in Django is a Python class that extends django.db.models.Model.

      The Customer model will have these database fields:

      • first_name — The first name of the customer.
      • last_name — The last name of the customer.
      • email — The email address of the customer.
      • phone — The phone number of the customer.
      • address — The address of the customer.
      • description — The description of the customer.
      • createdAt — The date when the customer is added.

      We will also add the __str__() function, which defines how the model will be displayed. In our case, it will be with the customer's first name. For more on constructing classes and defining objects, please see How To Construct Classes and Define Objects in Python 3.

      Add the following code to the file:

      ~/djangoreactproject/customers/models.py

      from django.db import models
      
      class Customer(models.Model):
          first_name = models.CharField("First name", max_length=255)
          last_name = models.CharField("Last name", max_length=255)
          email = models.EmailField()
          phone = models.CharField(max_length=20)
          address =  models.TextField(blank=True, null=True)
          description = models.TextField(blank=True, null=True)
          createdAt = models.DateTimeField("Created At", auto_now_add=True)
      
          def __str__(self):
              return self.first_name
      

      Next, migrate the database to create the database tables. The makemigrations command creates the migration files where model changes will be added, and migrate applies the changes in the migrations files to the database.

      Navigate back to the project's root folder:

      Run the following to create the migration files:

      • python manage.py makemigrations

      You will get output that looks like this:

      Output

      customers/migrations/0001_initial.py - Create model Customer

      Apply these changes to the database:

      You will see output indicating a successful migration:

      Output

      Operations to perform: Apply all migrations: admin, auth, contenttypes, customers, sessions Running migrations: Applying customers.0001_initial... OK

      Next, you will use a data migration file to create initial customer data. A data migration file is a migration that adds or alters data in the database. Create an empty data migration file for the customers application:

      • python manage.py makemigrations --empty --name customers customers

      You will see the following confirmation with the name of your migration file:

      Output

      Migrations for 'customers': customers/migrations/0002_customers.py

      Note that the name of your migration file is 0002_customers.py.

      Next, navigate inside the migrations folder of the customers application:

      • cd ~/djangoreactproject/customers/migrations

      Open the created migration file:

      This is the initial content of the file:

      ~/djangoreactproject/customers/migrations/0002_customers.py

      from django.db import migrations
      
      class Migration(migrations.Migration):
          dependencies = [
              ('customers', '0001_initial'),
          ]
          operations = [
          ]        
      

      The import statement imports the migrations API, a Django API for creating migrations, from django.db, a built-in package that contains classes for working with databases.

      The Migration class is a Python class that describes the operations that are executed when migrating databases. This class extends migrations.Migration and has two lists:

      • dependencies: Contains the dependent migrations.
      • operations: Contains the operations that will be executed when we apply the migration.

      Next, add a method to create demo customer data. Add the following method before the definition of the Migration class:

      ~/djangoreactproject/customers/migrations/0002_customers.py

      ...
      def create_data(apps, schema_editor):
          Customer = apps.get_model('customers', 'Customer')
          Customer(first_name="Customer 001", last_name="Customer 001", email="customer001@email.com", phone="00000000", address="Customer 000 Address", description= "Customer 001 description").save()
      
      ...
      

      In this method, we are grabbing the Customer class of our customers app and creating a demo customer to insert into the database.

      To get the Customer class, which will enable the creation of new customers, we use the get_model() method of the apps object. The apps object represents the registry of installed applications and their database models.

      The apps object will be passed from the RunPython() method when we use it to run create_data(). Add the migrations.RunPython() method to the empty operations list:

      ~/djangoreactproject/customers/migrations/0002_customers.py

      
      ...
          operations = [
              migrations.RunPython(create_data),
          ]  
      

      RunPython() is part of the Migrations API that allows you to run custom Python code in a migration. Our operations list specifies that this method will be executed when we apply the migration.

      This is the complete file:

      ~/djangoreactproject/customers/migrations/0002_customers.py

      from django.db import migrations
      
      def create_data(apps, schema_editor):
          Customer = apps.get_model('customers', 'Customer')
          Customer(first_name="Customer 001", last_name="Customer 001", email="customer001@email.com", phone="00000000", address="Customer 000 Address", description= "Customer 001 description").save()
      
      class Migration(migrations.Migration):
          dependencies = [
              ('customers', '0001_initial'),
          ]
          operations = [
              migrations.RunPython(create_data),
          ]        
      

      For more information on data migrations, see the documentation on data migrations in Django

      To migrate your database, first navigate back to the root folder of your project:

      Migrate your database to create the demo data:

      You will see output that confirms the migration:

      Output

      Operations to perform: Apply all migrations: admin, auth, contenttypes, customers, sessions Running migrations: Applying customers.0002_customers... OK

      For more details on this process, refer back to How To Create Django Models.

      With the Customer model and demo data created, we can move on to building the REST API.

      Step 5 — Creating the REST API

      In this step we'll create the REST API using the Django REST Framework. We'll create several different API views. An API view is a function that handles an API request or call, while an API endpoint is a unique URL that represents a touchpoint with the REST system. For example, when the user sends a GET request to an API endpoint, Django calls the corresponding function or API view to handle the request and return any possible results.

      We'll also make use of serializers. A serializer in the Django REST Framework allows complex model instances and QuerySets to be converted into JSON format for API consumption. The serializer class can also work in the other direction, providing mechanisms for parsing and deserializing data into Django models and QuerySets.

      Our API endpoints will include:

      • api/customers: This endpoint is used to create customers and returns paginated sets of customers.
      • api/customers/<pk>: This endpoint is used to get, update, and delete single customers by primary key or id.

      We'll also create URLs in the project's urls.py file for the corresponding endpoints (i.e api/customers and api/customers/<pk>).

      Let's start by creating the serializer class for our Customer model.

      Adding the Serializer Class

      Creating a serializer class for our Customer model is necessary for transforming customer instances and QuerySets to and from JSON. To create the serializer class, first make a serializers.py file inside the customers application:

      • cd ~/djangoreactproject/customers/
      • nano serializers.py

      Add the following code to import the serializers API and Customer model:

      ~/djangoreactproject/customers/serializers.py

      from rest_framework import serializers
      from .models import Customer
      

      Next, create a serializer class that extends serializers.ModelSerializer and specifies the fields that will be serialized:

      ~/djangoreactproject/customers/serializers.py

      
      ...
      class CustomerSerializer(serializers.ModelSerializer):
      
          class Meta:
              model = Customer 
              fields = ('pk','first_name', 'last_name', 'email', 'phone','address','description')
      

      The Meta class specifies the model and fields to serialize: pk,first_name, last_name, email, phone, address,description.

      This is the full content of the file:

      ~/djangoreactproject/customers/serializers.py

      from rest_framework import serializers
      from .models import Customer
      
      class CustomerSerializer(serializers.ModelSerializer):
      
          class Meta:
              model = Customer 
              fields = ('pk','first_name', 'last_name', 'email', 'phone','address','description')
      

      Now that we've created our serializer class, we can add the API views.

      Adding the API Views

      In this section, we'll create the API views for our application that will be called by Django when the user visits the endpoint corresponding to the view function.

      Open ~/djangoreactproject/customers/views.py:

      • nano ~/djangoreactproject/customers/views.py

      Delete what's there and add the following imports:

      ~/djangoreactproject/customers/views.py

      from rest_framework.response import Response
      from rest_framework.decorators import api_view
      from rest_framework import status
      
      from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger
      from .models import Customer 
      from .serializers import *
      

      We are importing the serializer we created, along with the Customer model and the Django and Django REST Framework APIs.

      Next, add the view for processing POST and GET HTTP requests:

      ~/djangoreactproject/customers/views.py

      ...
      
      @api_view(['GET', 'POST'])
      def customers_list(request):
          """
       List  customers, or create a new customer.
       """
          if request.method == 'GET':
              data = []
              nextPage = 1
              previousPage = 1
              customers = Customer.objects.all()
              page = request.GET.get('page', 1)
              paginator = Paginator(customers, 10)
              try:
                  data = paginator.page(page)
              except PageNotAnInteger:
                  data = paginator.page(1)
              except EmptyPage:
                  data = paginator.page(paginator.num_pages)
      
              serializer = CustomerSerializer(data,context={'request': request} ,many=True)
              if data.has_next():
                  nextPage = data.next_page_number()
              if data.has_previous():
                  previousPage = data.previous_page_number()
      
              return Response({'data': serializer.data , 'count': paginator.count, 'numpages' : paginator.num_pages, 'nextlink': '/api/customers/?page=' + str(nextPage), 'prevlink': '/api/customers/?page=' + str(previousPage)})
      
          elif request.method == 'POST':
              serializer = CustomerSerializer(data=request.data)
              if serializer.is_valid():
                  serializer.save()
                  return Response(serializer.data, status=status.HTTP_201_CREATED)
              return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
      

      First we use the @api_view(['GET', 'POST']) decorator to create an API view that can accept GET and POST requests. A decorator is a function that takes another function and dynamically extends it.

      In the method body we use the request.method variable to check the current HTTP method and execute the corresponding logic depending on the request type:

      • If it's a GET request, the method paginates the data using Django Paginator, and returns the first page of data after serialization, the count of available customers, the number of available pages, and the links to the previous and next pages. Paginator is a built-in Django class that paginates a list of data into pages and provides methods to access the items for each page.
      • If it's a POST request, the method serializes the received customer data and then calls the save() method of the serializer object. It then returns a Response object, an instance of HttpResponse, with a 201 status code. Each view you create is responsible for returing an HttpResponse object. The save() method saves the serialized data in the database.

      For more about HttpResponse and views, see this discussion of creating view functions.

      Now add the API view that will be responsible for processing the GET, PUT, and DELETE requests for getting, updating, and deleting customers by pk (primary key):

      ~/djangoreactproject/customers/views.py

      
      ...
      @api_view(['GET', 'PUT', 'DELETE'])
      def customers_detail(request, pk):
       """
       Retrieve, update or delete a customer by id/pk.
       """
          try:
              customer = Customer.objects.get(pk=pk)
          except Customer.DoesNotExist:
              return Response(status=status.HTTP_404_NOT_FOUND)
      
          if request.method == 'GET':
              serializer = CustomerSerializer(customer,context={'request': request})
              return Response(serializer.data)
      
          elif request.method == 'PUT':
              serializer = CustomerSerializer(customer, data=request.data,context={'request': request})
              if serializer.is_valid():
                  serializer.save()
                  return Response(serializer.data)
              return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
      
          elif request.method == 'DELETE':
              customer.delete()
              return Response(status=status.HTTP_204_NO_CONTENT)
      

      The method is decorated with @api_view(['GET', 'PUT', 'DELETE']) to denote that it's an API view that can accept GET, PUT, and DELETE requests.

      The check in the request.method field verifies the request method, and depending on its value calls the right logic:

      • If it's a GET request, customer data is serialized and sent using a Response object.
      • If it's a PUT request, the method creates a serializer for new customer data. Next, it calls the save() method of the created serializer object. Finally, it sends a Response object with the updated customer.
      • If it's a DELETE request, the method calls the delete() method of the customer object to delete it, then returns a Response object with no data.

      The completed file looks like this:

      ~/djangoreactproject/customers/views.py

      from rest_framework.response import Response
      from rest_framework.decorators import api_view
      from rest_framework import status
      
      from django.core.paginator import Paginator, EmptyPage, PageNotAnInteger
      from .models import Customer 
      from .serializers import *
      
      
      @api_view(['GET', 'POST'])
      def customers_list(request):
          """
       List  customers, or create a new customer.
       """
          if request.method == 'GET':
              data = []
              nextPage = 1
              previousPage = 1
              customers = Customer.objects.all()
              page = request.GET.get('page', 1)
              paginator = Paginator(customers, 5)
              try:
                  data = paginator.page(page)
              except PageNotAnInteger:
                  data = paginator.page(1)
              except EmptyPage:
                  data = paginator.page(paginator.num_pages)
      
              serializer = CustomerSerializer(data,context={'request': request} ,many=True)
              if data.has_next():
                  nextPage = data.next_page_number()
              if data.has_previous():
                  previousPage = data.previous_page_number()
      
              return Response({'data': serializer.data , 'count': paginator.count, 'numpages' : paginator.num_pages, 'nextlink': '/api/customers/?page=' + str(nextPage), 'prevlink': '/api/customers/?page=' + str(previousPage)})
      
          elif request.method == 'POST':
              serializer = CustomerSerializer(data=request.data)
              if serializer.is_valid():
                  serializer.save()
                  return Response(serializer.data, status=status.HTTP_201_CREATED)
              return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
      
      @api_view(['GET', 'PUT', 'DELETE'])
      def customers_detail(request, pk):
          """
       Retrieve, update or delete a customer by id/pk.
       """
          try:
              customer = Customer.objects.get(pk=pk)
          except Customer.DoesNotExist:
              return Response(status=status.HTTP_404_NOT_FOUND)
      
          if request.method == 'GET':
              serializer = CustomerSerializer(customer,context={'request': request})
              return Response(serializer.data)
      
          elif request.method == 'PUT':
              serializer = CustomerSerializer(customer, data=request.data,context={'request': request})
              if serializer.is_valid():
                  serializer.save()
                  return Response(serializer.data)
              return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
      
          elif request.method == 'DELETE':
              customer.delete()
              return Response(status=status.HTTP_204_NO_CONTENT)
      

      We can now move on to creating our endpoints.

      Adding API Endpoints

      We will now create the API endpoints: api/customers/, for querying and creating customers, and api/customers/<pk>, for getting, updating, or deleting single customers by their pk.

      Open ~/djangoreactproject/djangoreactproject/urls.py:

      • nano ~/djangoreactproject/djangoreactproject/urls.py

      Leave what's there, but add the import to the customers views at the top of the file:

      ~/djangoreactproject/djangoreactproject/urls.py

      from django.contrib import admin
      from django.urls import path
      from customers import views
      from django.conf.urls import url
      

      Next, add the api/customers/ and api/customers/<pk> URLs to the urlpatterns list that contains the application's URLs:

      ~/djangoreactproject/djangoreactproject/urls.py

      ...
      
      urlpatterns = [
          path('admin/', admin.site.urls),
          url(r'^api/customers/$', views.customers_list),
          url(r'^api/customers/(?P<pk>[0-9]+)$', views.customers_detail),
      ]
      

      With our REST endpoints created, let's see how we can consume them.

      Step 6 — Consuming the REST API with Axios

      In this step, we'll install Axios, the HTTP client we'll use to make API calls. We'll also create a class to consume the API endpoints we've created.

      First, deactivate your virtual environment:

      Next, navigate to your frontend folder:

      • cd ~/djangoreactproject/frontend

      Install axios from npm using:

      The --save option adds the axios dependency to your application's package.json file.

      Next, create a JavaScript file called CustomersService.js, which will contain the code to call the REST APIs. We'll make this inside the src folder, where the application code for our project will live:

      • cd src
      • nano CustomersService.js

      Add the following code, which contains methods to connect to the Django REST API:

      ~/djangoreactproject/frontend/src/CustomersService.js

      import axios from 'axios';
      const API_URL = 'http://localhost:8000';
      
      export default class CustomersService{
      
          constructor(){}
      
      
          getCustomers() {
              const url = `${API_URL}/api/customers/`;
              return axios.get(url).then(response => response.data);
          }  
          getCustomersByURL(link){
              const url = `${API_URL}${link}`;
              return axios.get(url).then(response => response.data);
          }
          getCustomer(pk) {
              const url = `${API_URL}/api/customers/${pk}`;
              return axios.get(url).then(response => response.data);
          }
          deleteCustomer(customer){
              const url = `${API_URL}/api/customers/${customer.pk}`;
              return axios.delete(url);
          }
          createCustomer(customer){
              const url = `${API_URL}/api/customers/`;
              return axios.post(url,customer);
          }
          updateCustomer(customer){
              const url = `${API_URL}/api/customers/${customer.pk}`;
              return axios.put(url,customer);
          }
      }
      

      The CustomersService class will call the following Axios methods:

      • getCustomers(): Gets first page of customers.
      • getCustomersByURL(): Gets customers by URL. This makes it possible to get the next pages of customers by passing links such as /api/customers/?page=2.
      • getCustomer(): Gets a customer by primary key.
      • createCustomer(): Creates a customer.
      • updateCustomer(): Updates a customer.
      • deleteCustomer(): Deletes a customer.

      We can now display the data from our API in our React UI interface by creating a CustomersList component.

      Step 7 — Displaying Data from the API in the React Application

      In this step, we'll create the CustomersList React component. A React component represents a part of the UI; it also lets you split the UI into independent, reusable pieces.

      Begin by creating CustomersList.js in frontend/src:

      • nano ~/djangoreactproject/frontend/src/CustomersList.js

      Start by importing React and Component to create a React component:

      ~/djangoreactproject/frontend/src/CustomersList.js

      import  React, { Component } from  'react';
      

      Next, import and instantiate the CustomersService module you created in the previous step, which provides methods that interface with the REST API backend:

      ~/djangoreactproject/frontend/src/CustomersList.js

      
      ...
      import  CustomersService  from  './CustomersService';
      
      const  customersService  =  new  CustomersService();
      

      Next, create a CustomersList component that extends Component to call the REST API. A React component should extend or subclass the Component class. For more about E6 classes and inheritence, please see our tutorial on Understanding Classes in JavaScript.

      Add the following code to create a React component that extends react.Component:

      ~/djangoreactproject/frontend/src/CustomersList.js

      
      ...
      class  CustomersList  extends  Component {
      
          constructor(props) {
              super(props);
              this.state  = {
                  customers: [],
                  nextPageURL:  ''
              };
              this.nextPage  =  this.nextPage.bind(this);
              this.handleDelete  =  this.handleDelete.bind(this);
          }
      }
      export  default  CustomersList;
      

      Inside the constructor, we are initializing the state object. This holds the state variables of our component using an empty customers array. This array will hold customers and a nextPageURL that will hold the URL of the next page to retrieve from the back-end API. We are also binding the nextPage() and handleDelete() methods to this so they will be accessible from the HTML code.

      Next, add the componentDidMount() method and a call to getCustomers() within the CustomersList class, before the closing curly brace.

      The componentDidMount() method is a lifecycle method of the component that is called when the component is created and inserted into the DOM. getCustomers() calls the Customers Service object to get the first page of data and the link of the next page from the Django backend:

      ~/djangoreactproject/frontend/src/CustomersList.js

      
      ...
      componentDidMount() {
          var  self  =  this;
          customersService.getCustomers().then(function (result) {
              self.setState({ customers:  result.data, nextPageURL:  result.nextlink})
          });
      }
      

      Now add the handleDelete() method, which handles deleting a customer, below componentDidMount():

      ~/djangoreactproject/frontend/src/CustomersList.js

      
      ...
      handleDelete(e,pk){
          var  self  =  this;
          customersService.deleteCustomer({pk :  pk}).then(()=>{
              var  newArr  =  self.state.customers.filter(function(obj) {
                  return  obj.pk  !==  pk;
              });
              self.setState({customers:  newArr})
          });
      }
      

      The handleDelete() method calls the deleteCustomer() method to delete a customer using its pk (primary key). If the operation is successful, the customers array is filtered out for the removed customer.

      Next, add a nextPage() method to get the data for the next page and update the next page link:

      ~/djangoreactproject/frontend/src/CustomersList.js

      
      ...
      nextPage(){
          var  self  =  this;
          customersService.getCustomersByURL(this.state.nextPageURL).then((result) => {
              self.setState({ customers:  result.data, nextPageURL:  result.nextlink})
          });
      }
      

      The nextPage() method calls a getCustomersByURL() method, which takes the next page URL from the state object, this.state.nextPageURL, and updates the customers array with the returned data.

      Finally, add the component render() method, which renders a table of customers from the component state:

      ~/djangoreactproject/frontend/src/CustomersList.js

      
      ...
      render() {
      
          return (
          <div  className="customers--list">
              <table  className="table">
                  <thead  key="thead">
                  <tr>
                      <th>#</th>
                      <th>First Name</th>
                      <th>Last Name</th>
                      <th>Phone</th>
                      <th>Email</th>
                      <th>Address</th>
                      <th>Description</th>
                      <th>Actions</th>
                  </tr>
                  </thead>
                  <tbody>
                      {this.state.customers.map( c  =>
                      <tr  key={c.pk}>
                          <td>{c.pk}  </td>
                          <td>{c.first_name}</td>
                          <td>{c.last_name}</td>
                          <td>{c.phone}</td>
                          <td>{c.email}</td>
                          <td>{c.address}</td>
                          <td>{c.description}</td>
                          <td>
                          <button  onClick={(e)=>  this.handleDelete(e,c.pk) }> Delete</button>
                          <a  href={"/customer/" + c.pk}> Update</a>
                          </td>
                      </tr>)}
                  </tbody>
              </table>
              <button  className="btn btn-primary"  onClick=  {  this.nextPage  }>Next</button>
          </div>
          );
      }
      

      This is the full content of the file:

      ~/djangoreactproject/frontend/src/CustomersList.js

      import  React, { Component } from  'react';
      import  CustomersService  from  './CustomersService';
      
      const  customersService  =  new  CustomersService();
      
      class  CustomersList  extends  Component {
      
      constructor(props) {
          super(props);
          this.state  = {
              customers: [],
              nextPageURL:  ''
          };
          this.nextPage  =  this.nextPage.bind(this);
          this.handleDelete  =  this.handleDelete.bind(this);
      }
      
      componentDidMount() {
          var  self  =  this;
          customersService.getCustomers().then(function (result) {
              console.log(result);
              self.setState({ customers:  result.data, nextPageURL:  result.nextlink})
          });
      }
      handleDelete(e,pk){
          var  self  =  this;
          customersService.deleteCustomer({pk :  pk}).then(()=>{
              var  newArr  =  self.state.customers.filter(function(obj) {
                  return  obj.pk  !==  pk;
              });
      
              self.setState({customers:  newArr})
          });
      }
      
      nextPage(){
          var  self  =  this;
          console.log(this.state.nextPageURL);        
          customersService.getCustomersByURL(this.state.nextPageURL).then((result) => {
              self.setState({ customers:  result.data, nextPageURL:  result.nextlink})
          });
      }
      render() {
      
          return (
              <div  className="customers--list">
                  <table  className="table">
                  <thead  key="thead">
                  <tr>
                      <th>#</th>
                      <th>First Name</th>
                      <th>Last Name</th>
                      <th>Phone</th>
                      <th>Email</th>
                      <th>Address</th>
                      <th>Description</th>
                      <th>Actions</th>
                  </tr>
                  </thead>
                  <tbody>
                  {this.state.customers.map( c  =>
                      <tr  key={c.pk}>
                      <td>{c.pk}  </td>
                      <td>{c.first_name}</td>
                      <td>{c.last_name}</td>
                      <td>{c.phone}</td>
                      <td>{c.email}</td>
                      <td>{c.address}</td>
                      <td>{c.description}</td>
                      <td>
                      <button  onClick={(e)=>  this.handleDelete(e,c.pk) }> Delete</button>
                      <a  href={"/customer/" + c.pk}> Update</a>
                      </td>
                  </tr>)}
                  </tbody>
                  </table>
                  <button  className="btn btn-primary"  onClick=  {  this.nextPage  }>Next</button>
              </div>
              );
        }
      }
      export  default  CustomersList;
      

      Now that we've created the CustomersList component for displaying the list of customers, we can add the component that handles customer creation and updates.

      Step 8 — Adding the Customer Create and Update React Component

      In this step, we'll create the CustomerCreateUpdate component, which will handle creating and updating customers. It will do this by providing a form that users can use to either enter data about a new customer or update an existing entry.

      In frontend/src, create a CustomerCreateUpdate.js file:

      • nano ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      Add the following code to create a React component, importing React and Component:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      import  React, { Component } from  'react';
      

      We can also import and instantiate the CustomersService class we created in the previous step, which provides methods that interface with the REST API backend:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      ...
      import  CustomersService  from  './CustomersService';
      
      const  customersService  =  new  CustomersService();
      

      Next, create a CustomerCreateUpdate component that extends Component to create and update customers:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      
      ...
      class  CustomerCreateUpdate  extends  Component {
      
          constructor(props) {
              super(props);
          }
      
      }
      export default CustomerCreateUpdate;
      

      Within the class definition, add the render() method of the component, which renders an HTML form that takes information about the customer:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      
      ...
      render() {
              return (
                <form onSubmit={this.handleSubmit}>
                <div className="form-group">
                  <label>
                    First Name:</label>
                    <input className="form-control" type="text" ref='firstName' />
      
                  <label>
                    Last Name:</label>
                    <input className="form-control" type="text" ref='lastName'/>
      
                  <label>
                    Phone:</label>
                    <input className="form-control" type="text" ref='phone' />
      
                  <label>
                    Email:</label>
                    <input className="form-control" type="text" ref='email' />
      
                  <label>
                    Address:</label>
                    <input className="form-control" type="text" ref='address' />
      
                  <label>
                    Description:</label>
                    <textarea className="form-control" ref='description' ></textarea>
      
      
                  <input className="btn btn-primary" type="submit" value="Submit" />
                  </div>
                </form>
              );
        }
      

      For each form input element, the method adds a ref property to access and set the value of the form element.

      Next, above the render() method, define a handleSubmit(event) method so that you have the proper functionality when a user clicks on the submit button:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      
      ...
      handleSubmit(event) {
          const { match: { params } } =  this.props;
          if(params  &&  params.pk){
              this.handleUpdate(params.pk);
          }
          else
          {
              this.handleCreate();
          }
          event.preventDefault();
      }
      
      ...
      

      The handleSubmit(event) method handles the form submission and, depending on the route, calls either the handleUpdate(pk) method to update the customer with the passed pk, or the handleCreate() method to create a new customer. We will define these methods shortly.

      Back on the component constructor, bind the newly added handleSubmit() method to this so you can access it in your form:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      ...
      class CustomerCreateUpdate extends Component {
      
      constructor(props) {
          super(props);
          this.handleSubmit = this.handleSubmit.bind(this);
      }
      ...
      

      Next, define the handleCreate() method to create a customer from the form data. Above the handleSubmit(event) method, add the following code:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      
      ...
      handleCreate(){
          customersService.createCustomer(
              {
              "first_name":  this.refs.firstName.value,
              "last_name":  this.refs.lastName.value,
              "email":  this.refs.email.value,
              "phone":  this.refs.phone.value,
              "address":  this.refs.address.value,
              "description":  this.refs.description.value
              }).then((result)=>{
                      alert("Customer created!");
              }).catch(()=>{
                      alert('There was an error! Please re-check your form.');
              });
      }
      
      ...
      

      The handleCreate() method will be used to create a customer from inputted data. It calls the corresponding CustomersService.createCustomer() method that makes the actual API call to the backend to create a customer.

      Next, below the handleCreate() method, define the handleUpdate(pk) method to implement updates:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      
      ...
      handleUpdate(pk){
      customersService.updateCustomer(
          {
          "pk":  pk,
          "first_name":  this.refs.firstName.value,
          "last_name":  this.refs.lastName.value,
          "email":  this.refs.email.value,
          "phone":  this.refs.phone.value,
          "address":  this.refs.address.value,
          "description":  this.refs.description.value
          }
          ).then((result)=>{
      
              alert("Customer updated!");
          }).catch(()=>{
              alert('There was an error! Please re-check your form.');
          });
      }
      

      The updateCustomer() method will update a customer by pk using the new information from the customer information form. It calls the customersService.updateCustomer() method.

      Next, add a componentDidMount() method. If the the user visits a customer/:pk route, we want to fill the form with information related to the customer using the primary key from the URL. To do that, we can add the getCustomer(pk) method after the component gets mounted in the lifecycle event of componentDidMount(). Add the following code below the component constructor to add this method:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      
      ...
      componentDidMount(){
          const { match: { params } } =  this.props;
          if(params  &&  params.pk)
          {
              customersService.getCustomer(params.pk).then((c)=>{
                  this.refs.firstName.value  =  c.first_name;
                  this.refs.lastName.value  =  c.last_name;
                  this.refs.email.value  =  c.email;
                  this.refs.phone.value  =  c.phone;
                  this.refs.address.value  =  c.address;
                  this.refs.description.value  =  c.description;
              })
          }
      }
      

      This is the full content of the file:

      ~/djangoreactproject/frontend/src/CustomerCreateUpdate.js

      import React, { Component } from 'react';
      import CustomersService from './CustomersService';
      
      const customersService = new CustomersService();
      
      class CustomerCreateUpdate extends Component {
          constructor(props) {
              super(props);
      
              this.handleSubmit = this.handleSubmit.bind(this);
            }
      
            componentDidMount(){
              const { match: { params } } = this.props;
              if(params && params.pk)
              {
                customersService.getCustomer(params.pk).then((c)=>{
                  this.refs.firstName.value = c.first_name;
                  this.refs.lastName.value = c.last_name;
                  this.refs.email.value = c.email;
                  this.refs.phone.value = c.phone;
                  this.refs.address.value = c.address;
                  this.refs.description.value = c.description;
                })
              }
            }
      
            handleCreate(){
              customersService.createCustomer(
                {
                  "first_name": this.refs.firstName.value,
                  "last_name": this.refs.lastName.value,
                  "email": this.refs.email.value,
                  "phone": this.refs.phone.value,
                  "address": this.refs.address.value,
                  "description": this.refs.description.value
              }          
              ).then((result)=>{
                alert("Customer created!");
              }).catch(()=>{
                alert('There was an error! Please re-check your form.');
              });
            }
            handleUpdate(pk){
              customersService.updateCustomer(
                {
                  "pk": pk,
                  "first_name": this.refs.firstName.value,
                  "last_name": this.refs.lastName.value,
                  "email": this.refs.email.value,
                  "phone": this.refs.phone.value,
                  "address": this.refs.address.value,
                  "description": this.refs.description.value
              }          
              ).then((result)=>{
                console.log(result);
                alert("Customer updated!");
              }).catch(()=>{
                alert('There was an error! Please re-check your form.');
              });
            }
            handleSubmit(event) {
              const { match: { params } } = this.props;
      
              if(params && params.pk){
                this.handleUpdate(params.pk);
              }
              else
              {
                this.handleCreate();
              }
      
              event.preventDefault();
            }
      
            render() {
              return (
                <form onSubmit={this.handleSubmit}>
                <div className="form-group">
                  <label>
                    First Name:</label>
                    <input className="form-control" type="text" ref='firstName' />
      
                  <label>
                    Last Name:</label>
                    <input className="form-control" type="text" ref='lastName'/>
      
                  <label>
                    Phone:</label>
                    <input className="form-control" type="text" ref='phone' />
      
                  <label>
                    Email:</label>
                    <input className="form-control" type="text" ref='email' />
      
                  <label>
                    Address:</label>
                    <input className="form-control" type="text" ref='address' />
      
                  <label>
                    Description:</label>
                    <textarea className="form-control" ref='description' ></textarea>
      
      
                  <input className="btn btn-primary" type="submit" value="Submit" />
                  </div>
                </form>
              );
            }  
      }
      
      export default CustomerCreateUpdate;
      

      With the CustomerCreateUpdate component created, we can update the main App component to add links to the different components we've created.

      Step 9 — Updating the Main App Component

      In this section, we'll update the App component of our application to create links to the components we've created in the previous steps.

      From the frontend folder, run the following command to install the React Router, which allows you to add routing and navigation between various React components:

      • cd ~/djangoreactproject/frontend
      • npm install --save react-router-dom

      Next, open ~/djangoreactproject/frontend/src/App.js:

      • nano ~/djangoreactproject/frontend/src/App.js

      Delete everything that's there and add the following code to import the necessary classes for adding routing. These include BrowserRouter, which creates a Router component, and Route, which creates a route component:

      ~/djangoreactproject/frontend/src/App.js

      import  React, { Component } from  'react';
      import { BrowserRouter } from  'react-router-dom'
      import { Route, Link } from  'react-router-dom'
      import  CustomersList  from  './CustomersList'
      import  CustomerCreateUpdate  from  './CustomerCreateUpdate'
      import  './App.css';
      

      BrowserRouter keeps the UI in sync with the URL using the HTML5 history API.

      Next, create a base layout that provides the base component to be wrapped by the BrowserRouter component:

      ~/djangoreactproject/frontend/src/App.js

      ...
      
      const  BaseLayout  = () => (
      <div  className="container-fluid">
          <nav  className="navbar navbar-expand-lg navbar-light bg-light">
              <a  className="navbar-brand"  href="#">Django React Demo</a>
              <button  className="navbar-toggler"  type="button"  data-toggle="collapse"  data-target="#navbarNavAltMarkup"  aria-controls="navbarNavAltMarkup"  aria-expanded="false"  aria-label="Toggle navigation">
              <span  className="navbar-toggler-icon"></span>
          </button>
          <div  className="collapse navbar-collapse"  id="navbarNavAltMarkup">
              <div  className="navbar-nav">
                  <a  className="nav-item nav-link"  href="/">CUSTOMERS</a>
                  <a  className="nav-item nav-link"  href="http://www.digitalocean.com/customer">CREATE CUSTOMER</a>
              </div>
          </div>
          </nav>
          <div  className="content">
              <Route  path="/"  exact  component={CustomersList}  />
              <Route  path="/customer/:pk"  component={CustomerCreateUpdate}  />
              <Route  path="/customer/"  exact  component={CustomerCreateUpdate}  />
          </div>
      </div>
      )
      

      We use the Route component to define the routes of our application; the component the router should load once a match is found. Each route needs a path to specify the path to be matched and a component to specify the component to load. The exact property tells the router to match the exact path.

      Finally, create the App component, the root or top-level component of our React application:

      ~/djangoreactproject/frontend/src/App.js

      ...
      
      class  App  extends  Component {
      
      render() {
          return (
          <BrowserRouter>
              <BaseLayout/>
          </BrowserRouter>
          );
      }
      }
      export  default  App;
      

      We have wrapped the BaseLayout component with the BrowserRouter component since our app is meant to run in the browser.

      The completed file looks like this:

      ~/djangoreactproject/frontend/src/App.js

      import React, { Component } from 'react';
      import { BrowserRouter } from 'react-router-dom'
      import { Route, Link } from 'react-router-dom'
      
      import  CustomersList from './CustomersList'
      import  CustomerCreateUpdate  from './CustomerCreateUpdate'
      import './App.css';
      
      const BaseLayout = () => (
        <div className="container-fluid">
      <nav className="navbar navbar-expand-lg navbar-light bg-light">
        <a className="navbar-brand" href="#">Django React Demo</a>
        <button className="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavAltMarkup" aria-controls="navbarNavAltMarkup" aria-expanded="false" aria-label="Toggle navigation">
          <span className="navbar-toggler-icon"></span>
        </button>
        <div className="collapse navbar-collapse" id="navbarNavAltMarkup">
          <div className="navbar-nav">
            <a className="nav-item nav-link" href="/">CUSTOMERS</a>
            <a className="nav-item nav-link" href="http://www.digitalocean.com/customer">CREATE CUSTOMER</a>
      
          </div>
        </div>
      </nav>  
      
          <div className="content">
            <Route path="/" exact component={CustomersList} />
            <Route path="/customer/:pk"  component={CustomerCreateUpdate} />
            <Route path="/customer/" exact component={CustomerCreateUpdate} />
      
          </div>
      
        </div>
      )
      
      class App extends Component {
        render() {
          return (
            <BrowserRouter>
              <BaseLayout/>
            </BrowserRouter>
          );
        }
      }
      
      export default App;
      

      After adding routing to our application, we are now ready to test the application. Navigate to http://localhost:3000. You should see the first page of the application:

      Application Home Page

      With this application in place, you now have the base for a CRM application.

      Conclusion

      In this tutorial, you created a demo application using Django and React. You used the Django REST framework to build the REST API, Axios to consume the API, and Bootstrap 4 to style your CSS. You can find the source code of this project in this GitHub repository.

      This tutorial setup used separate front-end and back-end apps. For a different approach to integrating React with Django, check this tutorial and this tutorial.

      For more information about building an application with Django, you can follow the Django development series. You can also look at the official Django docs.



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