Fixed #8279 -- Multiple many-to-many relations to "self" are now possible.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8721 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick 2008-08-29 21:24:00 +00:00
parent ae953a8c4e
commit f04123f4df
3 changed files with 66 additions and 1 deletions

View File

@ -716,7 +716,7 @@ class OneToOneField(ForeignKey):
SingleRelatedObjectDescriptor(related)) SingleRelatedObjectDescriptor(related))
if not cls._meta.one_to_one_field: if not cls._meta.one_to_one_field:
cls._meta.one_to_one_field = self cls._meta.one_to_one_field = self
def formfield(self, **kwargs): def formfield(self, **kwargs):
if self.rel.parent_link: if self.rel.parent_link:
return None return None
@ -844,6 +844,15 @@ class ManyToManyField(RelatedField, Field):
return smart_unicode(data) return smart_unicode(data)
def contribute_to_class(self, cls, name): def contribute_to_class(self, cls, name):
# To support multiple relations to self, it's useful to have a non-None
# related name on symmetrical relations for internal reasons. The
# concept doesn't make a lot of sense externally ("you want me to
# specify *what* on my non-reversible relation?!"), so we set it up
# automatically. The funky name reduces the chance of an accidental
# clash.
if self.rel.symmetrical and self.rel.related_name is None:
self.rel.related_name = "%s_rel_+" % name
super(ManyToManyField, self).contribute_to_class(cls, name) super(ManyToManyField, self).contribute_to_class(cls, name)
# Add the descriptor for the m2m relation # Add the descriptor for the m2m relation
setattr(cls, self.name, ReverseManyRelatedObjectsDescriptor(self)) setattr(cls, self.name, ReverseManyRelatedObjectsDescriptor(self))

View File

@ -0,0 +1,56 @@
from django.db import models
# No related name is needed here, since symmetrical relations are not
# explicitly reversible.
class SelfRefer(models.Model):
name = models.CharField(max_length=10)
references = models.ManyToManyField('self')
related = models.ManyToManyField('self')
def __unicode__(self):
return self.name
class Tag(models.Model):
name = models.CharField(max_length=10)
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):
name = models.CharField(max_length=10)
topics = models.ManyToManyField(Tag)
related = models.ManyToManyField(Tag, related_name="similar")
def __unicode__(self):
return self.name
__test__ = {"regressions": """
# Multiple m2m references to the same model or a different model must be
# distinguished when accessing the relations through an instance attribute.
>>> s1 = SelfRefer.objects.create(name='s1')
>>> s2 = SelfRefer.objects.create(name='s2')
>>> s3 = SelfRefer.objects.create(name='s3')
>>> s1.references.add(s2)
>>> s1.related.add(s3)
>>> e1 = Entry.objects.create(name='e1')
>>> t1 = Tag.objects.create(name='t1')
>>> t2 = Tag.objects.create(name='t2')
>>> e1.topics.add(t1)
>>> e1.related.add(t2)
>>> s1.references.all()
[<SelfRefer: s2>]
>>> s1.related.all()
[<SelfRefer: s3>]
>>> e1.topics.all()
[<Tag: t1>]
>>> e1.related.all()
[<Tag: t2>]
"""
}