Query with FilteredRelation

[qdelcourte]

Hi! I tried using Django FilteredRelation with a PolymorphicQueryset and I got an error https://docs.djangoproject.com/en/3.1/ref/models/querysets/#filteredrelation-objects

Some PolymorphicModel:

from django.db import models
from polymorphic.models import PolymorphicModel

class ModelA(PolymorphicModel):
    comment = models.CharField(max_length=255, blank=True)

class ModelB(ModelA):
    modelC = models.ForeignKey('ModelC', on_delete=models.CASCADE)

Basic query with FilteredRelation:

from django.db.models import FilteredRelation, Q

ModelB.objects.annotate(test=FilteredRelation('modelC', condition=Q()))

Got this error:

  File "/usr/local/lib/python3.7/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/polymorphic/query.py", line 307, in annotate
    self._process_aggregate_args(args, kwargs)
  File "/usr/local/lib/python3.7/site-packages/polymorphic/query.py", line 302, in _process_aggregate_args
    patch_lookup(a)
  File "/usr/local/lib/python3.7/site-packages/polymorphic/query.py", line 273, in patch_lookup
    a.name = translate_polymorphic_field_path(self.model, a.name)
AttributeError: 'FilteredRelation' object has no attribute 'name'