How do we add and save additional parameters to a serializer object in django rest framework?

Question

These are the field in my PostSerializer

fields = ('id','user_id','title','desc','comments')

The user_id and comments are code generated and title,desc were obtained from api calls. I want to pass this as additional values to my request.data. This is my APIView object

class PostView(APIView):
    permission_classes = (IsAuthenticated,) 
    def post(self,request):
        request.data['user_id'] = request.user.id
        request.data['comments'] = "machine generated"
        post_serializer = PostSerializer(data=request.data)
        if post_serializer.is_valid():
            post_serializer.save()
            print(request.data)
            return Response(post_serializer.data)

While my print(request.data) shows user_id,comments fields and their corresponding values. In the saved database though the values for user_id and comments are null.

How do we add and save additional parameters to a serializer object in django rest framework?

Answer 1

Method 1
You can pass additional fields to serializer.save() as follows:

class PostView(APIView):
    permission_classes = (IsAuthenticated,) 
    def post(self,request):
        post_serializer = PostSerializer(data=request.data)
        if post_serializer.is_valid():
            post_serializer.save (
            
            user_id=request.user_id,
            comments="machine generated"
            
            )
            return Response(post_serializer.data)

But through this method, you should make blank=True for user_id, comments to make serializer valid.

Method 2
I'm not sure this method works correctly, but i recommend you to not change request.data. first copy that and then make changes to new dictionary. as follows:

class PostView(APIView):
    permission_classes = (IsAuthenticated,) 
    def post(self,request):
        data = dict(request.data)
        data['user_id'] = request.user.id
        data['comments'] = "machine generated"

        post_serializer = PostSerializer(data=data)
        if post_serializer.is_valid():
            post_serializer.save()
            return Response(post_serializer.data)

Method 3
You can change request.data with .update() method without losing data from client side:

class PostView(APIView):
    permission_classes = (IsAuthenticated,) 
    def post(self,request):
        request.data.update ( {

            'user_id': request.user.id,
            'comments': "machine generated text"

        } )

        post_serializer = PostSerializer(data=request.data)
        if post_serializer.is_valid():
            post_serializer.save()
            print(request.data)
            return Response(post_serializer.data)