From ac0aea8910ec72a874ccd859a4f6449a895f4ec0 Mon Sep 17 00:00:00 2001
From: Russell Keith-Magee <russell@keith-magee.com>
Date: Fri, 2 Apr 2010 15:52:58 +0000
Subject: [PATCH] [1.1.X] Fixed #11956 -- Modified the handling of m2m
 relationships between subclasses. Thanks to nidi for the report, and
 astoneman for the suggestion on how to fix the problem.

Backport of r12908 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12909 bcc190cf-cafb-0310-a4f2-bffc1f526a37
---
 django/db/models/fields/related.py          |  4 ++--
 tests/regressiontests/m2m_regress/models.py | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 008f5b6ac0..795292f279 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -606,7 +606,7 @@ class ReverseManyRelatedObjectsDescriptor(object):
             model=rel_model,
             core_filters={'%s__pk' % self.field.related_query_name(): instance._get_pk_val()},
             instance=instance,
-            symmetrical=(self.field.rel.symmetrical and isinstance(instance, rel_model)),
+            symmetrical=self.field.rel.symmetrical,
             join_table=qn(self.field.m2m_db_table()),
             source_col_name=qn(self.field.m2m_column_name()),
             target_col_name=qn(self.field.m2m_reverse_name())
@@ -804,7 +804,7 @@ class ManyToManyField(RelatedField, Field):
         kwargs['rel'] = ManyToManyRel(to,
             related_name=kwargs.pop('related_name', None),
             limit_choices_to=kwargs.pop('limit_choices_to', None),
-            symmetrical=kwargs.pop('symmetrical', True),
+            symmetrical=kwargs.pop('symmetrical', to==RECURSIVE_RELATIONSHIP_CONSTANT),
             through=kwargs.pop('through', None))
 
         self.db_table = kwargs.pop('db_table', None)
diff --git a/tests/regressiontests/m2m_regress/models.py b/tests/regressiontests/m2m_regress/models.py
index 7f6da3341b..5453d396ae 100644
--- a/tests/regressiontests/m2m_regress/models.py
+++ b/tests/regressiontests/m2m_regress/models.py
@@ -17,6 +17,13 @@ class Tag(models.Model):
     def __unicode__(self):
         return self.name
 
+# Regression for #11956 -- a many to many to the base class
+class TagCollection(Tag):
+    tags = models.ManyToManyField(Tag, related_name='tag_collections')
+
+    def __unicode__(self):
+        return self.name
+
 # A related_name is required on one of the ManyToManyField entries here because
 # they are both addressable as reverse relations from Tag.
 class Entry(models.Model):
@@ -102,5 +109,17 @@ FieldError: Cannot resolve keyword 'porcupine' into field. Choices are: id, name
 >>> w.save()
 >>> w.delete()
 
+# Regression for #11956 -- You can add an object to a m2m with the
+# base class without causing integrity errors
+>>> c1 = TagCollection.objects.create(name='c1')
+>>> c1.tags = [t1,t2]
+
+>>> c1 = TagCollection.objects.get(name='c1')
+>>> c1.tags.all()
+[<Tag: t1>, <Tag: t2>]
+
+>>> t1.tag_collections.all()
+[<TagCollection: c1>]
+
 """
 }