Throttling Specific Actions in Django Rest Framework Viewsets

19 May 2017 code

If you are using rate limiting with Django Rest Framework you probably already know that it provides some pretty simple methods for setting global rate limits using DEFAULT_THROTTLE_RATES. You can also set rate limits for specific views using the throttle_classes property on class-based views or the @throttle_classes decorator for function based views.

What if you are using ViewSets but want different throttling rules to apply to different actions? Unfortunately DRF provides no official method of doing this. Luckily we can accomplish this functionality without too much fuss.

The solution comes from combining the ScopedRateThrottle throttle class with the get_throttles() method of APIView.

In our ViewSet let's override the get_throttles() method:

    class FooViewSet(viewsets.ModelViewSet):
        queryset = Foo.objects.all()
        serializer_class = FooSerializer

        def get_throttles(self):
            if self.action in ['delete', 'validate']:
                self.throttle_scope = 'foo.' + self.action
            return super().get_throttles()

        @list_route()
        def validate(self, request):
            return Response('Validation!')

What we are doing here is pretty simple: checking to see if the action being performed is one we want to throttle , and if so, setting the throttle_scope property on the ViewSet.

This alone won't do anything (in fact it will error) so let's add the necessary config to settings.py to make it work:

    REST_FRAMEWORK = {
        'DEFAULT_THROTTLE_CLASSES': (
            'rest_framework.throttling.UserRateThrottle',
            'rest_framework.throttling.ScopedRateThrottle',
        ),
        'DEFAULT_THROTTLE_RATES': {
            'user': '5000/day',
            'foo.delete': '100/day',
            'foo.validate': '10000/day'
        }
    }

The magic is contained within the ScopedRateThrottle. This class will look for the throttle_scope property on the view, and if found, look up a corresponding key in the DEFAULT_THROTTLE_RATES dictionary.

Notice that the keys are namespaced with .foo. This isn't necessary, but if you're using more than one ViewSet and you don't want the rules to apply to all of them, you should namespace them.

There you have it, throttling for ViewSets.

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