Check out this snippet of code (the second one). If this does not suit your need, please add some of your code (for better understanding).

UPDATE

For routing, DRF offers a default router for each view. This means that you can have the following configuration in your urls.py: (using the example from the previous link)

url(r'^users/count/$', views. UserCountView.as_view(), name='users-count')

Then, when you access the URL your_base_url/users/count/ you will see something like {'user_count': 10}.

UPDATE 2

The entire code should look like this:

class UserCountView(APIView):
    """
    A view that returns the count of active users.
    """
    renderer_classes = (JSONRenderer, )

    def get(self, request, format=None):
        user_count = User.objects.count()
        content = {'user_count': user_count}
        return Response(content)

I am using routers from REST Framework to build my URLs. I tried above code but doesn't get it working. One of the problems is I cannot get /count/ into the router endpoints.

I checked DRF document (3.8.2) and found that there is a (new?) @action decorator (I was using 3.7.7 and it doesn't have it). So, here is my full solutions:

1. Upgrade DRF to 3.8.2 (or above) in requirements.txt (or PipFile if you using that).
2. Add a new action count method to the ModelViewSet
3. Update get_permissions to include the newly added action count

Here is my views.py:

from rest_framework.decorators import action
from rest_framework.response import Response

class PostViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows recommend to be viewed or edited.
    """
    model = Post
    queryset = Post.objects.filter(is_active=True)
    serializer_class = serializers.PostSerializer
    filter_backends = (filters.SearchFilter, DjangoFilterBackend,)
    search_fields = ('title', 'body',)
    filter_fields = ('status', 'type')

    def get_permissions(self):
        if self.action in ('list', 'retrieve', 'create', 'count'):
            return (AllowAny()),
        if self.action in ('update', 'partial_update'):
            return (IsAdminUser()),
        return (IsAdminUser()),

    @action(detail=False)
    def count(self, request):
        queryset = self.filter_queryset(self.get_queryset())
        count = queryset.count()
        content = {'count': count}
        return Response(content)

• To query count of posts: /api/posts/count/?format=json
• To query count of published: /api/posts/count/?format=json&status=published

One of the important thing here is to use the queryset from filter_queryset(...), rather than Post.objects.all().

UPDATE

Since count is common, I created a mixin for that.

from rest_framework.decorators import action
from rest_framework.response import Response

class CountModelMixin(object):
    """
    Count a queryset.
    """
    @action(detail=False)
    def count(self, request, *args, **kwargs):
        queryset = self.filter_queryset(self.get_queryset())
        content = {'count': queryset.count()}
        return Response(content)

To use it, just add CountModelMixin to your ModelViewSet (also support nested ModelViewSet).

class PostViewSet(viewsets.ModelViewSet, CountModelMixin):

If you use permissions, also add 'count' to the list of granted action.