Django rest framework best way to validate POST request parameters

Question

When I receive a POST request on a Django REST framework APIView class, I would like to filter/validate the parameters that are passed to prevent them from being modified. For example, for this serializer:

class MediaSerializer(serializers.ModelSerializer):
    class Meta:
        model = Media
        fields = ('id', 'title', 'content', 'url', 'createdByUser', 'karma', 'type', 'issue', 'creationDate', 'updatedDate')

Some parameters such as the id, creationDate or createdByUser shouldn't be modified. So for my class class MediaDetail(APIView) I have:

def validateRequest(self):
        user = self.request.data.get('createdByUser', None)
        karma = self.request.data.get('karma', None)
        creationDate = self.request.data.get('creationDate', None)

        if user is not None or karma is not None or creationDate is not None:
            return Response(status=status.HTTP_400_BAD_REQUEST)

@method_decorator(login_required)
def post(self, request, pk, format=None):
        self.validateRequest()
        media = self.get_object(pk)
        self._throwIfNotMediaAuthor(media, request.user)

        serializer = MediaSerializer(media, data=request.data)

        if serializer.is_valid():
            # serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

Is there a better way to make this validation? Maybe on the serializer? I couldn't find enough documentation.

Answer 1

Yes, you can use the read_only_fields parameter on your serializer's Meta.

Example on how to use inside your current view (modified it a little assuming you want to create an object when POSTing as per REST's guidelines):

class MediaSerializer(serializers.ModelSerializer):
    class Meta:
        model = Media
        read_only_fields = ('id', 'karma', 'createdByUser', 'creationDate')
        ...

@method_decorator(login_required)
def post(self, request, pk, format=None):
        serializer = MediaSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        serializer.save(createdByUser=request.user, creationDate=timezone.now().date(), karma=initial_value)
        return Response(serializer.data, status=status.HTTP_201_CREATED)