def update creates a new one but does not update - Django

Question

I have a method to create a new item in my database that works fine. But the similar method that updates, is creating a new item and not updating, and if I force the id to pass in "data", it complains that this id already exists...

My CODE:

class EventsAttachViewSet(
    mixins.ListModelMixin,
    mixins.CreateModelMixin,
    mixins.UpdateModelMixin,
    mixins.DestroyModelMixin,
    mixins.RetrieveModelMixin,
    viewsets.GenericViewSet
):
    permission_classes = [permissions.AllowAny]
    queryset = EventAttachment.objects.all()
    serializer_class = EventAttachmentSerializer

    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        data = serializer.validated_data
        self.perform_create(serializer)
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

    def update(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        data = serializer.validated_data
        self.perform_update(serializer)
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

Answer 1

Here you need to pass instance of an object for update.

def update(self, request, *args, **kwargs):
        instance = self.get_object()
        serializer = self.get_serializer(instance, data=request.data)
        serializer.is_valid(raise_exception=True)
        data = serializer.validated_data
        self.perform_update(serializer)
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)