#26797: Reverse `related_name` of a proxy not accessible to inherited proxies
-------------------------------------+-------------------------------------
Reporter: mlorant | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.9
(models, ORM) | Keywords: related_name reverse
Severity: Normal | relation
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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Taken the following example (not real world use case, but it is somewhat
equivalent of something I encountered):
{{{
from django.db import models
class Animal(models.Model):
name = models.CharField("animal name", max_length=255, blank=True,
null=False)
class Mammal(Animal):
class Meta:
proxy = True
class Cat(Mammal):
class Meta:
proxy = True
class Dog(Mammal):
class Meta:
proxy = True
class TrueFriendship(models.Model):
mammal = models.ForeignKey(Mammal, related_name="dog_friends")
dog = models.ForeignKey(Dog, related_name="mammal_friends")
}}}
I want to get the number of friends of a queryset of cats. However, doing
this in a shell results in an exception:
{{{
>>> from nature.models import *
>>> cat = Cat.objects.create(name="cat1")
>>> dog = Dog.objects.create(name="dog1")
>>> TrueFriendship.objects.create(cat=cat, dog=dog)
>>> Cat.objects.annotate(nb_dog_friends=models.Count('dog_friends'))
Traceback (most recent call last):
File "/data/.virtualenvs/bugproxy/local/lib/python2.7/site-
packages/django/db/models/manager.py", line 122, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
[...]
File "/data/.virtualenvs/bugproxy/local/lib/python2.7/site-
packages/django/db/models/sql/query.py", line 1330, in names_to_path
"Choices are: %s" % (name, ", ".join(available)))
FieldError: Cannot resolve keyword 'dog_friends' into field. Choices are:
id, name
}}}
(Full traceback attached in a file) However, the same query using the
`Mammal` proxy works and the reverse relation is available on single
object:
{{{
>>>
Mammal.objects.annotate(nb_dog_friends=models.Count('dog_friends')).first().nb_dog_friends
1
>>> Cat.objects.first().dog_friends.all()
[<TrueFriendship: TrueFriendship object>]
}}}
Something is inconsistent here: I would expect to have access to
`dog_friends` in both cases (on a model instance and a queryset)
--
Ticket URL: <https://code.djangoproject.com/ticket/26797>
Django <https://code.djangoproject.com/>
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