Dummy Serializer in Django Rest Framework

Dummy serializer is the serializer used in viewset having no actual implementation or use case.

For example we have a viewset called ContentViewSet. This viewset gives user access to content such as article, quiz, video etc. Now, we have a action called user_content_log which stores the log of user on our database. This logs can be really helpful in identifying user recent watched or viewed content.

User Content Log Action under ContentViewSet

@action(detail=True, methods=['post'], url_path='user-content-log')
def user_content_log(self, \*args, \*\*kwargs):
content = self.get_object()
user = self.request.user
from datetime import datetime
UserContentLog.objects.update_or_create(user=user,
content=content, defaults={'updated_at': datetime.now()})
return Response({
'Video log created!'
}, status=status.HTTP_200_OK)

The above code shows the action to store user content log. The UserContentLog model requires only two fields content and user. Since the action is written under ContentViewSet and the detail field is set to True, we can get the content object from self.get_object() and the user field is available in request.user. In such a case, we do not require a serializer for validation as both fields are available to backend.

ContentViewSet Serializer Class

def get_serializer_class(self):
return ContentSerializer

Now, though we do not require a serializer class for action, we require a serializer class for viewset. If we do not provide a serializer class for user_content_log action, ContentViewSet serializer class which is ContentSerializer will be used by default.

Is it really a big problem?

The short answer is No. It does not make a big difference. Neither will this raise an error because the serializer class is never called inside our user_content_log action. But this will prevents us from wrong swagger docs. Since the user_content_log action is using a wrong serializer class, the swagger docs will show false information.

So what can we do?

We can make a dummy serializer class like shown below:

class DummySerializer(serializers.Serializer): # dummy serializer for using when serializer class # is needed in viewset but actual serializer is not used # for maintaining swagger doc
pass

And we can override the get_serializer_class of ContentViewSet and provide DummySerializer to user_content_log action.

def get_serializer_class(self):
if self.action == 'user_content_log':
return DummySerializer
return ContentSerializer

Bravo! we are done. Now the swagger docs does not show false information as the serializer for user_content_log action is DummySerializer.