FilterSet nested queryset not working as expected

[mohse...@gmail.com]

Hello

I've created an issue on github, and now posting here to bring discussion to group as @johnraz suggested.

lets see the sim code:

# views.py
class ProductViewSet(ModelViewSet):
    queryset = Product.objects.all()
    serializer_class = ProductSerializer

    filter_backends = (filters.DjangoFilterBackend, filters.OrderingFilter,)
    filter_class = ProductFilter

    def get_queryset(self):
        queryset = super().get_queryset()
        if self.request.method == 'GET':
            brand_id = self.request.query_params.get('brand_id', None)
            if brand_id:
                queryset = queryset.prefetch_related(Prefetch('resources', queryset=Resource.objects.filter(brand_id=brand_id)))
            else:
                queryset = queryset.prefetch_related('resources')
        return queryset

# filters.py
class ProductFilter(django_filters.FilterSet):
    brand_id = django_filters.NumberFilter('resources__brand_id')
    min_score = django_filters.NumberFilter('resources__score', lookup_type='gte', distinct=True)
    class Meta:
        model = Product

# models.py
class Resource(models.Model):
    brand = models.ForeignKey(Brand, related_name='resources')

    score = models.FloatField(null=True)

    # Generic relation to Product and like.
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.IntegerField()
    content_object = GenericForeignKey('content_type', 'object_id')

class Product(models.Model):
        resources = GenericRelation(Resource, related_query_name='product')

when someone query Product endpoint with 'brand_id=100&min_score=45', it means "give me the Products that have a resource with brand_id 100 and scored more that 45". but the result set contains products that have any resource scored more than 45, whether it's brand_id is 100 or not. it seems that ProductFilter class ignores view queryset modifications and creates the queryset from the original model.

any help would be highly appreciated.