Fixed #12885 -- Fixed queries with GenericRelations to multi-table inheritance child models.

This commit is contained in:
Anssi Kääriäinen 2015-10-27 13:13:16 +02:00 committed by Tim Graham
parent 4cd24bb67c
commit cd0ba8053d
2 changed files with 45 additions and 2 deletions

View File

@ -359,10 +359,46 @@ class GenericRelation(ForeignObject):
self.to_fields = [self.model._meta.pk.name]
return [(self.remote_field.model._meta.get_field(self.object_id_field_name), self.model._meta.pk)]
def _get_path_info_with_parent(self):
"""
Return the path that joins the current model through any parent models.
The idea is that if you have a GFK defined on a parent model then we
need to join the parent model first, then the child model.
"""
# With an inheritance chain ChildTag -> Tag and Tag defines the
# GenericForeignKey, and a TaggedItem model has a GenericRelation to
# ChildTag, then we need to generate a join from TaggedItem to Tag
# (as Tag.object_id == TaggedItem.pk), and another join from Tag to
# ChildTag (as that is where the relation is to). Do this by first
# generating a join to the parent model, then generating joins to the
# child models.
path = []
opts = self.remote_field.model._meta
parent_opts = opts.get_field(self.object_id_field_name).model._meta
target = parent_opts.pk
path.append(PathInfo(self.model._meta, parent_opts, (target,), self.remote_field, True, False))
# Collect joins needed for the parent -> child chain. This is easiest
# to do if we collect joins for the child -> parent chain and then
# reverse the direction (call to reverse() and use of
# field.remote_field.get_path_info()).
parent_field_chain = []
while parent_opts != opts:
field = opts.get_ancestor_link(parent_opts.model)
parent_field_chain.append(field)
opts = field.remote_field.model._meta
parent_field_chain.reverse()
for field in parent_field_chain:
path.extend(field.remote_field.get_path_info())
return path
def get_path_info(self):
opts = self.remote_field.model._meta
target = opts.pk
return [PathInfo(self.model._meta, opts, (target,), self.remote_field, True, False)]
object_id_field = opts.get_field(self.object_id_field_name)
if object_id_field.model != opts.model:
return self._get_path_info_with_parent()
else:
target = opts.pk
return [PathInfo(self.model._meta, opts, (target,), self.remote_field, True, False)]
def get_reverse_path_info(self):
opts = self.model._meta

View File

@ -405,6 +405,13 @@ class GenericRelationsTests(TestCase):
# GenericRelations to models that use multi-table inheritance work.
granite = ValuableRock.objects.create(name='granite', hardness=5)
ValuableTaggedItem.objects.create(content_object=granite, tag="countertop", value=1)
self.assertEqual(ValuableRock.objects.filter(tags__value=1).count(), 1)
# We're generating a slightly inefficient query for tags__tag - we
# first join ValuableRock -> TaggedItem -> ValuableTaggedItem, and then
# we fetch tag by joining TaggedItem from ValuableTaggedItem. The last
# join isn't necessary, as TaggedItem <-> ValuableTaggedItem is a
# one-to-one join.
self.assertEqual(ValuableRock.objects.filter(tags__tag="countertop").count(), 1)
granite.delete() # deleting the rock should delete the related tag.
self.assertEqual(ValuableTaggedItem.objects.count(), 0)