How to return custom JSON in Django REST Framework

Question

I am trying to return custom json with get_queryset but always get 404 error in response.

class TestViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows groups to be viewed or edited.
    """
    queryset = Test.objects.all()
    serializer_class = TestSerializer

    def get_queryset(self):
        if self.request.method == "GET":
            content = {'user_count': '2'}
            return HttpResponse(json.dumps(content), content_type='application/json')

If I delete everything starting from def I'll got correct response with standard json data. What I am doing wrong?

Answer 1

If you don't need a ModelViewSet and just want custom JSON on a GET request

You can also use an APIView, which doesn't require a model

class MyOwnView(APIView):
    def get(self, request):
        return Response({'some': 'data'})

and

urlpatterns = [
    url(r'^my-own-view/$', MyOwnView.as_view()),
]

With a ModelViewSet

You've put the custom JSON into get_queryset, that's wrong. If you want to use a ModelViewSet, this by itself should be enough:

class TestViewSet(viewsets.ModelViewSet):
    queryset = Test.objects.all()
    serializer_class = TestSerializer

This ModelViewSet comes with default implementations for .list(), .retrieve(), .create(), .update(), and .destroy(). Which are available for you to override (customize) as needed

Returning custom JSON from .retrieve() and/or .list() in ModelViewSet

E.g. to override .retrieve() to return custom view when retrieving a single object. We can have a look at the default implementation which looks like this:

def retrieve(self, request, *args, **kwargs):
    instance = self.get_object()
    serializer = self.get_serializer(instance)
    return Response(serializer.data)

So as an example to return custom JSON:

class TestViewSet(viewsets.ModelViewSet):
    queryset = Test.objects.all()
    serializer_class = TestSerializer

    def retrieve(self, request, *args, **kwargs):
        return Response({'something': 'my custom JSON'})

    def list(self, request, *args, **kwargs):
        return Response({'something': 'my custom JSON'})