Django-3.1/DRF/React: Unable to save nested images (linked through GenericRelation)

Question

I am building a Django+DRF/React app (simple blog app) and i am facing difficulties saving nested images

Model Structure

• Model:
  • Post
• Children:
  • details: ContentType Model ( DRF: save is successfull )
  • images: ContentType Model ( DRF : save is not successfull )

Process

• Send images from <input type="file" multiple />

• Process data through FormData

• Catch request.data and process it

  class PostFormView(generics.RetrieveUpdateDestroyAPIView):
      queryset = Post._objects.is_active()
      serializer_class = PostModelSerializer
      permission_classes = (IsOwnerOr401,)
      parser_classes = (parsers.MultiPartParser,parsers.JSONParser,
                  parsers.FormParser, parsers.FileUploadParser)
      lookup_field = 'slug'
      lookup_url_kwarg = 'slug'
  
      def get_queryset(self):
           return super().get_queryset().annotate(**sharedAnnotations(request=self.request))
  
      def update(self, request, *args, **kwargs):
  
           data = request.data
           _images = data.getlist('images')
           images = []
           for _ in _images:
               if isinstance(_, dict):
                   images.append(images)
                   continue
               images.append({'image': _, 'object_id': self.get_object().pk, 'content_type': self.get_object().get_content_type().pk})
  
            data['images'] = images
  
            print(data)
  
            partial = kwargs.pop('partial', False)
            instance = self.get_object()
            serializer = self.get_serializer(instance, data=data,  partial=partial)
            serializer.is_valid(raise_exception=True)
            self.perform_update(serializer)
  
            if getattr(instance, '_prefetched_objects_cache', None):
                instance._prefetched_objects_cache = {}
  
            return Response(serializer.data)
  

• Save images (FAIL):

  class MediaModelSerializer(ContentTypeModelSerializer):
       # inherits object_id & content_type fields just to avoid writing them over and over alongside (create & update fns)
       class Meta:
           model = Media 
           fields='__all__'
  
  
  class PostModelSerializer(WritableNestedModelSerializer):
  
      is_active = serializers.BooleanField(default=True)
      path = serializers.HyperlinkedIdentityField(
      view_name="api:post-detail", lookup_field='slug')
  
      images = MediaModelSerializer(many=True)
      details = DetailModelSerializer(required=False, many=True)
  
      # annotated fields
      is_author = serializers.BooleanField(read_only=True, default=False)
  
      class Meta:
          model = Post
          fields = '__all__'
          read_only_fields = ['is_locked', 'slug', 'user', 'is_author']
  
      def create(self, validated_data):
          return super().create(validated_data)
  
      def update(self, instance, validated_data):
          return super().update(instance, validated_data)
  

• The print(data) statement from PostFormView.update(self, request, *args, **kwargs) (after manipulation) returns this:

  <QueryDict: {'id': ['8'], ..., 'images': [[{'image': <InMemoryUploadedFile: bmw_3.jpeg (image/jpeg)>, 'object_id': 8, 'content_type': 20}, {'image': <InMemoryUploadedFile: bmw_2.jpeg (image/jpeg)>, 'object_id': 8, 'content_type': 20}, {'image': <InMemoryUploadedFile: bmw_1.jpeg (image/jpeg)>, 'object_id': 8, 'content_type': 20}]]}>
  

• Server returns 400_BAD_REQUEST because images were not passed to PostModelSerializer

  {"images":["This field is required."]}
  

i've been facing this issue for 3 days and i can't wrap my head around the root cause.

Thank you for your help.

Answer 1

i have been looking all over the internet but i could not find any anwsers so i had to go this way

I have removed the processing part from PostFormView.update(...) and accessed the images directly in the create & update methods of the ModelSerializer. I'll figure out later on how to handle removing these images

Here's the code:

class PostModelSerializer(WritableNestedModelSerializer):

    is_active = serializers.BooleanField(default=True)
    path = serializers.HyperlinkedIdentityField(
        view_name="api:post-detail", lookup_field='slug')

    images = MediaModelSerializer(read_only=True, many=True)
    details = DetailModelSerializer(required=False, many=True)

    # annotated fields
    is_author = serializers.BooleanField(read_only=True, default=False)

    class Meta:
        model = Post
        fields = '__all__'
        read_only_fields = ['is_locked', 'slug', 'user', 'is_author']

    def create(self, validated_data):
        instance = super().create(validated_data)

        request = self.context.get('request', None)
        if request:
            try:
                images = request.data.getlist('images')
                for image in images:
                    self.instance.images.create(image=image)
            except Exception as e:
                pass

        return instance

    def update(self, instance, validated_data):
        instance = super().update(instance, validated_data)
        
        request = self.context.get('request', None)
        if request:
            try:
                images = request.data.getlist('images')
                for image in images:
                    self.instance.images.create(image=image)
            except Exception as e:
                pass

        return instance

If anyone has faced this issue before and managed to resolve it, please post your answer below.

Thank you !