Function-Based API Views

from rest_framework.decorators import api_view
from rest_framework.response import Response
from .models import Book
from .serializers import BookSerializer

@api_view(['GET'])
def book_list(request):
    books = Book.objects.all()
    serializer = BookSerializer(books, many=True)
    return Response(serializer.data)

@api_view(['GET', 'POST'])
def book_list(request):
    if request.method == 'POST':
        serializer = BookSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=201)
        return Response(serializer.errors, status=400)
    books = Book.objects.all()
    return Response(BookSerializer(books, many=True).data)

from django.urls import path
from . import views

urlpatterns = [
    path('api/books/', views.book_list, name='book-list'),
]

1. Forgetting the @api_view([GET, POST]) decorator, which leaves the view unable to parse JSON request bodies or render DRF's Response objects correctly.
2. Returning a plain Django HttpResponse instead of DRF's Response, losing automatic content negotiation and the browsable API.
3. Not checking request.method inside a view that handles multiple HTTP methods, causing GET logic to run even on a POST request.

• @api_view([GET, POST]) marks a function as a DRF API view and restricts which HTTP methods it accepts.
• DRF's Response class replaces HttpResponse and automatically renders JSON (or the browsable API in a browser).
• Function-based API views branch on request.method just like regular Django views.