What are DRF viewsets and routers?

Question

Accepted Answer

In Django REST Framework, **viewsets** group the logic for a set of related API endpoints (the CRUD operations for a resource) into a single class, and **routers** automatically generate the URL routing for them. Together they dramatically reduce boilerplate for building RESTful APIs.

## ModelViewSet — full CRUD in a few lines

```python
from rest_framework import viewsets

class ArticleViewSet(viewsets.ModelViewSet):
    queryset = Article.objects.all()             # the data
    serializer_class = ArticleSerializer          # how to serialize it
    # That's it! This provides ALL standard CRUD endpoints automatically:
    #   list (GET), create (POST), retrieve (GET /id), update (PUT/PATCH /id), destroy (DELETE /id)
```

A `ModelViewSet` automatically provides the **complete set of RESTful CRUD endpoints** for a model — list, create, retrieve, update, partial update, and delete — from just a queryset and serializer. No need to write each view separately.

## Routers — automatic URL generation

```python
from rest_framework.routers import DefaultRouter

router = DefaultRouter()
router.register(r"articles", ArticleViewSet)     # register the viewset

urlpatterns = router.urls
# automatically creates the RESTful URLs:
#   GET    /articles/        → list
#   POST   /articles/        → create
#   GET    /articles/{id}/   → retrieve
#   PUT    /articles/{id}/   → update
#   PATCH  /articles/{id}/   → partial update
#   DELETE /articles/{id}/   → destroy
```

A **router** maps a viewset to a full set of standard RESTful URLs automatically — registering one viewset generates all the conventional endpoints with correct HTTP methods, eliminating manual URL configuration.

## Customizing viewsets

```python
class ArticleViewSet(viewsets.ModelViewSet):
    serializer_class = ArticleSerializer
    permission_classes = [IsAuthenticated]        # authorization

def get_queryset(self):                        # customize the data per request
        return Article.objects.filter(author=self.request.user)

# add CUSTOM endpoints beyond CRUD with @action
    @action(detail=True, methods=["post"])
    def publish(self, request, pk=None):           # POST /articles/{id}/publish/
        article = self.get_object()
        article.published = True
        article.save()
        return Response({"status": "published"})
```

Viewsets are customized by overriding methods (`get_queryset`, `perform_create`), setting permissions, and adding **custom actions** (`@action`) for endpoints beyond standard CRUD.

## Viewsets vs generic API views

```text
ModelViewSet  → ALL CRUD in one class + router → least code for standard REST resources
Generic views (ListCreateAPIView, etc.) → more explicit, one class per endpoint group
APIView       → full manual control for non-standard/custom endpoints
→ Use viewsets+routers for conventional REST resources; generic/APIView for custom needs.
```

## Why it matters

Viewsets and routers are a powerful DRF feature for building RESTful APIs efficiently — they represent the highest level of abstraction for the extremely common case of exposing a model as a full REST resource, and understanding them is valuable for productive API development.

The key benefit is dramatic **boilerplate reduction**: a `ModelViewSet` plus a router gives you a complete, conventional REST API for a resource (all CRUD endpoints with correct HTTP methods and URLs) from just a queryset and serializer — replacing what would otherwise be many separate views and manual URL patterns.

This makes building standard REST APIs remarkably fast while ensuring **RESTful conventions** (consistent URL structure and HTTP method semantics) are followed automatically.

Viewsets remain flexible — you customize them by overriding methods (filtering the queryset per user, controlling permissions, hooking into create/update) and adding **custom actions** (`@action`) for endpoints beyond basic CRUD.

Understanding viewsets and routers, how they generate endpoints, how to customize them, and **when to use them** (conventional REST resources) versus more explicit generic views or APIView (custom/non-standard endpoints) is important practical knowledge for DRF development.

Since building REST APIs is a primary use of Django today, and viewsets+routers are the idiomatic, most-productive way to do it for standard resources, they're a frequently-used, important part of the DRF toolkit that lets developers build robust APIs with minimal code while retaining the flexibility to handle custom requirements.