I’m working with Django Rest Framework and encountered an issue with a ModelSerializer. I was trying to validate the ‘id’ field in request.data using a ModelSerializer, but found that serializer.validated_data was missing the ‘id’ field even though serializer.is_valid() returned True. I’ve since resolved the issue by switching to a simple Serializer, but I’m trying to understand why the ModelSerializer didn’t work as expected. Any insights would be appreciated.

Here’s the relevant code:

Viewset function:

@action(detail=False, methods=['post'])
    def listWatchlistitems(self, request):
        serializerWatchlist = WatchlistIdSerializer(data=request.data)
        user = request.user
        print(f'request.data: {request.data}')
        if serializerWatchlist.is_valid():
            print(f"serializerWatchlist.validated_data.get('id'): {serializerWatchlist.validated_data.get('id')}")
            try:
                watchlist = Watchlist.objects.get(id=serializerWatchlist.validated_data.get('id'))
                #queryset = WatchlistItem.objects.filter(watchlist=watchlist, user=user)
                queryset = WatchlistItem.objects.filter(watchlist=watchlist)
                serializer = WatchlistItemSerializer(queryset, many=True)
                return Response(serializer.data)
            except ObjectDoesNotExist:
                return Response({"error": "Watchlist with given id does not exist"}, status=status.HTTP_400_BAD_REQUEST)
        else:
            return Response(serializerWatchlist.errors, status=status.HTTP_400_BAD_REQUEST)

Watchlist model:

class Watchlist(models.Model):
    user = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
    name = models.CharField(max_length=200)

    def __str__(self):
        return self.name

Original ModelSerializer:

class WatchlistIdSerializer(serializers.ModelSerializer):
    class Meta:
        model = Watchlist
        fields = ['id']

Modified Serializer that resolved the issue:

class WatchlistIdSerializer(serializers.Serializer):
    id = serializers.IntegerField()