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Module 10 / Project 04 — REST Framework

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Focus

Django REST Framework (DRF) — serializers, viewsets, routers, and the browsable API.

Why this project exists

Django's template system renders HTML for browsers, but modern applications often need a JSON API for mobile apps, single-page applications, or third-party integrations. Django REST Framework adds this capability to Django. If you used FastAPI in Module 04, DRF is Django's equivalent: it provides serializers (like Pydantic models), viewsets (like route handlers), and routers (like FastAPI's path decorators).

DRF also includes a browsable API — a web interface where you can interact with your API directly in the browser, similar to FastAPI's /docs page.

Run

cd projects/modules/10-django-fullstack/04-rest-framework
python manage.py migrate
python manage.py createsuperuser
python manage.py runserver

Then open your browser to:

  • http://127.0.0.1:8000/api/ — API root (browsable API)
  • http://127.0.0.1:8000/api/books/ — list all books (JSON)
  • http://127.0.0.1:8000/api/authors/ — list all authors (JSON)
  • http://127.0.0.1:8000/admin/ — add books and authors via admin

Press Ctrl+C to stop the server.

Expected output

Visiting /api/books/ in a browser shows DRF's browsable API with a list of books in JSON format. You can create new books using the form at the bottom of the page. Visiting /api/books/1/ shows details for a single book.

Visiting /api/books/?format=json returns raw JSON:

[
    {
        "id": 1,
        "title": "Django for Beginners",
        "author": 1,
        "author_name": "William Vincent",
        "price": "39.99",
        "published_date": "2024-01-15"
    }
]

Alter it

  1. Add a search filter: install django-filter and add filterset_fields = ["author"] to BookViewSet. Users can then filter books by author: /api/books/?author=1.
  2. Add pagination: in settings.py, add REST_FRAMEWORK = {"DEFAULT_PAGINATION_CLASS": "rest_framework.pagination.PageNumberPagination", "PAGE_SIZE": 10}.
  3. Add a custom action to BookViewSet that returns only books under $20: use @action(detail=False) decorator.

Break it

  1. In BookSerializer, remove author_name from fields. Visit /api/books/. How does the response change?
  2. In urls.py, comment out router.register("books", ...). Visit /api/books/. What error do you get?
  3. Remove "rest_framework" from INSTALLED_APPS. Try running the server. What happens?

Fix it

  1. Add author_name back. SerializerMethodField adds computed (read-only) fields to the API response. Removing it from fields removes it from the output.
  2. Uncomment the router registration. DRF routers generate URL patterns automatically from viewsets. Without registration, the URL pattern does not exist.
  3. Add "rest_framework" back. DRF must be in INSTALLED_APPS because it includes templates (for the browsable API), static files, and app configuration.

Explain it

  1. What is a serializer? How does it compare to Pydantic models in FastAPI?
  2. What is the difference between a ViewSet and a regular Django view?
  3. What does a DRF router do? How does it generate URL patterns from viewsets?
  4. What is the browsable API? Why is it useful during development?

Mastery check

You can move on when you can:

  • create a serializer for any model with both model fields and computed fields,
  • create a ViewSet with full CRUD operations,
  • wire viewsets to URLs using a router,
  • use the browsable API to test all CRUD operations.

Next

Continue to 05-complete-app.