id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
36135	Prefetching a reverse GenericRelation raises AttributeError	john	Simon Charette	"I have some models in my app:

{{{
class User(models.Model):
    name = models.CharField()


class Project(models.Model):
    name = models.CharField()
    users = models.ManyToManyField('User', related_name='projects')


class Task(models.Model):
    name = models.CharField()
    project = models.ForeignKey('Project', on_delete=models.DO_NOTHING, related_name='tasks', null=True)

    link_entity_type = models.ForeignKey(ContentType, on_delete=models.DO_NOTHING, null=True, related_name='link_tasks')
    link_entity_id = models.IntegerField(null=True)
    link = GenericForeignKey('link_entity_type', 'link_entity_id')


class Version(models.Model):
    name = models.CharField()
    task = models.ForeignKey('Task', on_delete=models.DO_NOTHING, related_name='versions', null=True)


class Shot(models.Model):
    name = models.CharField()
    users = models.ManyToManyField('User', related_name='shots')

    link_tasks = GenericRelation(
        'Task',
        object_id_field='link_entity_id',
        content_type_field='link_entity_type'.format(field.name),
        related_query_name='link_Shot'
    )


class Asset(models.Model):
    name = models.CharField()
    users = models.ManyToManyField('User', related_name='assets')

    link_tasks = GenericRelation(
        'Task',
        object_id_field='link_entity_id',
        content_type_field='link_entity_type'.format(field.name),
        related_query_name='link_Asset'
    )
}}}

If I query Task and prefetch project and users, I will use:
{{{
query = Task.objects.all().prefetch_related('project__users')
for i in query:
    print(i.id)
}}}

This is ok, I can get the result.

But if I want to query Task and prefetch link_Shot and users
{{{
query = Task.objects.all().prefetch_related('link_Shot__users')
for i in query:
    print(i.id)
}}}
or
{{{
query = Version.objects.all().prefetch_related('task__link_Shot__users')
for i in query:
    print(i.id)
}}}


I got error:
{{{
Traceback (most recent call last):
  File ""/ela/workspace/xinghuan/issues/sins/sins2server/tmp/tst_query.py"", line 35, in <module>
    for i in query:
  File ""/UNC/fs_user_ws.ela.com/ela/workspace/xinghuan/issues/sins/sins2server/tmp/django/db/models/query.py"", line 398, in __iter__
    self._fetch_all()
  File ""/UNC/fs_user_ws.ela.com/ela/workspace/xinghuan/issues/sins/sins2server/tmp/django/db/models/query.py"", line 1883, in _fetch_all
    self._prefetch_related_objects()
  File ""/UNC/fs_user_ws.ela.com/ela/workspace/xinghuan/issues/sins/sins2server/tmp/django/db/models/query.py"", line 1273, in _prefetch_related_objects
    prefetch_related_objects(self._result_cache, *self._prefetch_related_lookups)
  File ""/UNC/fs_user_ws.ela.com/ela/workspace/xinghuan/issues/sins/sins2server/tmp/django/db/models/query.py"", line 2321, in prefetch_related_objects
    obj_list, additional_lookups = prefetch_one_level(
  File ""/UNC/fs_user_ws.ela.com/ela/workspace/xinghuan/issues/sins/sins2server/tmp/django/db/models/query.py"", line 2463, in prefetch_one_level
    ) = prefetcher.get_prefetch_queryset(instances, lookup.get_current_queryset(level))
  File ""/UNC/fs_user_ws.ela.com/ela/workspace/xinghuan/issues/sins/sins2server/tmp/django/db/models/fields/related_descriptors.py"", line 746, in get_prefetch_queryset
    instance = instances_dict[rel_obj_attr(rel_obj)]
  File ""/UNC/fs_user_ws.ela.com/ela/workspace/xinghuan/issues/sins/sins2server/tmp/django/db/models/fields/related.py"", line 750, in get_local_related_value
    return self.get_instance_value_for_fields(instance, self.local_related_fields)
  File ""/UNC/fs_user_ws.ela.com/ela/workspace/xinghuan/issues/sins/sins2server/tmp/django/db/models/fields/related.py"", line 772, in get_instance_value_for_fields
    ret.append(getattr(instance, field.attname))
AttributeError: 'Shot' object has no attribute 'link_entity_id'
}}}

The discussion link:
[https://forum.djangoproject.com/t/how-to-prefetch-a-genericforeignkey-with-manytomany-field/38168]

I'm using Django 4.2.16 and python 3.9.
I also tried Django 5.1.5 and python 3.10 and the error is same.

"	Bug	closed	contrib.contenttypes	5.1	Normal	fixed	prefetch	john	Ready for checkin	1	0	0	0	0	0