103 lines
2.6 KiB
Python
103 lines
2.6 KiB
Python
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# coding: utf-8
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"""
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Tests for some corner cases with deleting.
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"""
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from django.db import models
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class DefaultRepr(object):
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def __repr__(self):
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return u"<%s: %s>" % (self.__class__.__name__, self.__dict__)
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class A(DefaultRepr, models.Model):
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pass
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class B(DefaultRepr, models.Model):
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a = models.ForeignKey(A)
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class C(DefaultRepr, models.Model):
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b = models.ForeignKey(B)
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class D(DefaultRepr, models.Model):
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c = models.ForeignKey(C)
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a = models.ForeignKey(A)
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# Simplified, we have:
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# A
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# B -> A
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# C -> B
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# D -> C
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# D -> A
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# So, we must delete Ds first of all, then Cs then Bs then As.
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# However, if we start at As, we might find Bs first (in which
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# case things will be nice), or find Ds first.
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__test__ = {'API_TESTS': """
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# Due to the way that transactions work in the test harness,
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# doing m.delete() here can work but fail in a real situation,
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# since it may delete all objects, but not in the right order.
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# So we manually check that the order of deletion is correct.
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# Also, it is possible that the order is correct 'accidentally', due
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# solely to order of imports etc. To check this, we set the order
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# that 'get_models()' will retrieve to a known 'tricky' order, and
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# then try again with the reverse and try again. Slightly naughty
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# access to internals here.
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>>> from django.utils.datastructures import SortedDict
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>>> from django.db.models.loading import cache
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# Nice order
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>>> cache.app_models['delete'].keyOrder = ['a', 'b', 'c', 'd']
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>>> del A._meta._related_objects_cache
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>>> del B._meta._related_objects_cache
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>>> del C._meta._related_objects_cache
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>>> del D._meta._related_objects_cache
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>>> a1 = A()
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>>> a1.save()
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>>> b1 = B(a=a1)
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>>> b1.save()
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>>> c1 = C(b=b1)
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>>> c1.save()
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>>> d1 = D(c=c1, a=a1)
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>>> d1.save()
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>>> sd = SortedDict()
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>>> a1._collect_sub_objects(sd)
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>>> list(reversed(sd.keys()))
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[<class 'modeltests.delete.models.D'>, <class 'modeltests.delete.models.C'>, <class 'modeltests.delete.models.B'>, <class 'modeltests.delete.models.A'>]
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>>> a1.delete()
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# Same again with a known bad order
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>>> cache.app_models['delete'].keyOrder = ['d', 'c', 'b', 'a']
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>>> del A._meta._related_objects_cache
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>>> del B._meta._related_objects_cache
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>>> del C._meta._related_objects_cache
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>>> del D._meta._related_objects_cache
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>>> a2 = A()
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>>> a2.save()
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>>> b2 = B(a=a2)
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>>> b2.save()
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>>> c2 = C(b=b2)
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>>> c2.save()
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>>> d2 = D(c=c2, a=a2)
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>>> d2.save()
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>>> sd2 = SortedDict()
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>>> a2._collect_sub_objects(sd2)
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>>> list(reversed(sd2.keys()))
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[<class 'modeltests.delete.models.D'>, <class 'modeltests.delete.models.C'>, <class 'modeltests.delete.models.B'>, <class 'modeltests.delete.models.A'>]
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>>> a2.delete()
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"""
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}
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