OAuth2 is an authentication and authorization framework that allows users to share their private resources (such as photos, videos, and other data) stored on one site with another site without compromising security. In Django Rest Framework, OAuth2Authentication is an authentication class provided by the django-oauth-toolkit package that can be used to implement OAuth2 authentication in your RESTful APIs.

With OAuth2Authentication, users can grant third-party applications limited access to their resources without sharing their login credentials. Instead of sharing passwords, users grant access by authorizing the third-party application to access their resources. This authorization is granted through the use of access tokens.

When a user grants authorization, the OAuth2 provider generates an access token that the third-party application can use to access the user’s resources. This access token is short-lived and can be refreshed by the third-party application to continue accessing the user’s resources. The access token can also be revoked by the user at any time.

In Django Rest Framework, you can use the OAuth2Authentication class to implement OAuth2 authentication in your APIs. This authentication class is based on the oauth2_provider library, which provides the underlying OAuth2 functionality.

To use OAuth2Authentication, you need to:

  1. Install django-oauth-toolkit using pip.
  2. Add oauth2_provider to your INSTALLED_APPS in your Django settings file.
  3. Run migrations to create the necessary database tables.
  4. Add the OAuth2Authentication class to your REST framework settings.
  5. Configure your OAuth2 provider settings in your Django settings file.
  6. Create an OAuth2 application using the create_oauth2_app management command.
  7. Use the @protected_resource decorator to protect your API views.

Once you have set up OAuth2 authentication, third-party applications can use the access token to access the user’s resources, as long as the user has granted the necessary authorization. The OAuth2Authentication class will verify the access token and ensure that the third-party application only has access to the resources that the user has authorized.

A small project on OAuth2 Authentication in Django:

1. Create a new Django project and app:

django-admin startproject oauth2_demo
cd oauth2_demo
python manage.py startapp myapp

2. Install django-oauth-toolkit using pip:

pip install django-oauth-toolkit

3. Add oauth2_provider to your INSTALLED_APPS in your Django settings file:

INSTALLED_APPS = [
    # ...
    'oauth2_provider',
    'myapp',
    # ...
]

4. Run migrations to create the necessary database tables:

python manage.py migrate

5. Add the OAuth2 authentication classes to your REST framework settings:

REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION_CLASSES': (
        'oauth2_provider.contrib.rest_framework.OAuth2Authentication',
    ),
}

6. Configure your OAuth2 provider by adding the following settings to your Django settings file:

OAUTH2_PROVIDER = {
    'ACCESS_TOKEN_EXPIRE_SECONDS': 3600,
    'REFRESH_TOKEN_EXPIRE_SECONDS': 3600 * 24 * 365,
}

7. Create an OAuth2 application by running the following command:

python manage.py create_oauth2_app --client-type confidential --name "My App" --user <your_username>

8. Add the following views to your myapp/views.py file:

from rest_framework.views import APIView
from rest_framework.response import Response
from oauth2_provider.decorators import protected_resource


class MyApiView(APIView):
    @protected_resource()
    def get(self, request):
        return Response({'message': 'Hello, OAuth2 user!'})

9. Add the following URLs to your myapp/urls.py file:

from django.urls import path
from .views import MyApiView

urlpatterns = [
    path('api/', MyApiView.as_view()),
]

10. Run the Django development server:

python manage.py runserver

11. Open your web browser and go to http://127.0.0.1:8000/oauth2/applications/. Log in with your Django superuser account and create a new application. Fill in the required fields, such as name and client type.

12. Once you have created the application, you should see a client ID and secret. Copy these values and use them in the next step.

13. Use a tool like curl or Postman to send an OAuth2 authentication request to your API. Here’s an example curl command:

curl -X GET \
  'http://127.0.0.1:8000/api/?access_token=<your_access_token>'

Replace <your_access_token> with the access token generated by the OAuth2 provider.

That’s it! You should now be able to use OAuth2 authentication to protect your API endpoints in your Django project.