mirror of https://github.com/django/django.git
84 lines
2.4 KiB
Python
84 lines
2.4 KiB
Python
from django.db import models
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# No related name is needed here, since symmetrical relations are not
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# explicitly reversible.
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class SelfRefer(models.Model):
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name = models.CharField(max_length=10)
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references = models.ManyToManyField('self')
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related = models.ManyToManyField('self')
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def __unicode__(self):
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return self.name
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class Tag(models.Model):
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name = models.CharField(max_length=10)
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def __unicode__(self):
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return self.name
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# A related_name is required on one of the ManyToManyField entries here because
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# they are both addressable as reverse relations from Tag.
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class Entry(models.Model):
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name = models.CharField(max_length=10)
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topics = models.ManyToManyField(Tag)
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related = models.ManyToManyField(Tag, related_name="similar")
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def __unicode__(self):
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return self.name
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# Two models both inheriting from a base model with a self-referential m2m field
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class SelfReferChild(SelfRefer):
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pass
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class SelfReferChildSibling(SelfRefer):
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pass
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__test__ = {"regressions": """
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# Multiple m2m references to the same model or a different model must be
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# distinguished when accessing the relations through an instance attribute.
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>>> s1 = SelfRefer.objects.create(name='s1')
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>>> s2 = SelfRefer.objects.create(name='s2')
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>>> s3 = SelfRefer.objects.create(name='s3')
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>>> s1.references.add(s2)
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>>> s1.related.add(s3)
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>>> e1 = Entry.objects.create(name='e1')
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>>> t1 = Tag.objects.create(name='t1')
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>>> t2 = Tag.objects.create(name='t2')
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>>> e1.topics.add(t1)
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>>> e1.related.add(t2)
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>>> s1.references.all()
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[<SelfRefer: s2>]
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>>> s1.related.all()
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[<SelfRefer: s3>]
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>>> e1.topics.all()
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[<Tag: t1>]
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>>> e1.related.all()
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[<Tag: t2>]
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# The secret internal related names for self-referential many-to-many fields
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# shouldn't appear in the list when an error is made.
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>>> SelfRefer.objects.filter(porcupine='fred')
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Traceback (most recent call last):
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...
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FieldError: Cannot resolve keyword 'porcupine' into field. Choices are: id, name, references, related, selfreferchild, selfreferchildsibling
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# Test to ensure that the relationship between two inherited models
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# with a self-referential m2m field maintains symmetry
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>>> sr_child = SelfReferChild(name="Hanna")
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>>> sr_child.save()
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>>> sr_sibling = SelfReferChildSibling(name="Beth")
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>>> sr_sibling.save()
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>>> sr_child.related.add(sr_sibling)
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>>> sr_child.related.all()
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[<SelfRefer: Beth>]
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>>> sr_sibling.related.all()
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[<SelfRefer: Hanna>]
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"""
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}
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