Fixed bug with Model.delete() which did not always delete objects in the right order.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7722 bcc190cf-cafb-0310-a4f2-bffc1f526a37

tests/modeltests/delete/models.py

@@ -33,8 +33,46 @@ class D(DefaultRepr, models.Model):
 # However, if we start at As, we might find Bs first (in which 
 # case things will be nice), or find Ds first.
 
+# Some mutually dependent models, but nullable
+class E(DefaultRepr, models.Model):
+    f = models.ForeignKey('F', null=True, related_name='e_rel')
+
+class F(DefaultRepr, models.Model):
+    e = models.ForeignKey(E, related_name='f_rel')
+
 
 __test__ = {'API_TESTS': """
+# First, some tests for the datastructure we use
+
+>>> from django.db.models.query import CollectedObjects
+
+>>> g = CollectedObjects()
+>>> g.add("key1", 1, "item1", None)
+False
+>>> g["key1"]
+{1: 'item1'}
+>>> g.add("key2", 1, "item1", "key1")
+False
+>>> g.add("key2", 2, "item2", "key1")
+False
+>>> g["key2"]
+{1: 'item1', 2: 'item2'}
+>>> g.add("key3", 1, "item1", "key1")
+False
+>>> g.add("key3", 1, "item1", "key2")
+True
+>>> g.ordered_keys()
+['key3', 'key2', 'key1']
+
+>>> g.add("key2", 1, "item1", "key3")
+True
+>>> g.ordered_keys()
+Traceback (most recent call last):
+    ...
+CyclicDependency: There is a cyclic dependency of items to be processed.
+
+
+
 # Due to the way that transactions work in the test harness,
 # doing m.delete() here can work but fail in a real situation,
 # since it may delete all objects, but not in the right order.
@@ -42,11 +80,10 @@ __test__ = {'API_TESTS': """
 
 # Also, it is possible that the order is correct 'accidentally', due
 # solely to order of imports etc.  To check this, we set the order
-# that 'get_models()' will retrieve to a known 'tricky' order, and
-# then try again with the reverse and try again.  Slightly naughty
-# access to internals here.
+# that 'get_models()' will retrieve to a known 'nice' order, and
+# then try again with a known 'tricky' order.  Slightly naughty
+# access to internals here :-)
 
->>> from django.utils.datastructures import SortedDict
 >>> from django.db.models.loading import cache
 
 # Nice order
@@ -56,8 +93,6 @@ __test__ = {'API_TESTS': """
 >>> del C._meta._related_objects_cache
 >>> del D._meta._related_objects_cache
 
-
-
 >>> a1 = A()
 >>> a1.save()
 >>> b1 = B(a=a1)
@@ -67,9 +102,9 @@ __test__ = {'API_TESTS': """
 >>> d1 = D(c=c1, a=a1)
 >>> d1.save()
 
->>> sd = SortedDict()
->>> a1._collect_sub_objects(sd)
->>> list(reversed(sd.keys()))
+>>> o = CollectedObjects()
+>>> a1._collect_sub_objects(o)
+>>> o.keys()
 [<class 'modeltests.delete.models.D'>, <class 'modeltests.delete.models.C'>, <class 'modeltests.delete.models.B'>, <class 'modeltests.delete.models.A'>]
 >>> a1.delete()
 
@@ -80,7 +115,6 @@ __test__ = {'API_TESTS': """
 >>> del C._meta._related_objects_cache
 >>> del D._meta._related_objects_cache
 
-
 >>> a2 = A()
 >>> a2.save()
 >>> b2 = B(a=a2)
@@ -90,13 +124,56 @@ __test__ = {'API_TESTS': """
 >>> d2 = D(c=c2, a=a2)
 >>> d2.save()
 
->>> sd2 = SortedDict()
->>> a2._collect_sub_objects(sd2)
->>> list(reversed(sd2.keys()))
+>>> o = CollectedObjects()
+>>> a2._collect_sub_objects(o)
+>>> o.keys()
 [<class 'modeltests.delete.models.D'>, <class 'modeltests.delete.models.C'>, <class 'modeltests.delete.models.B'>, <class 'modeltests.delete.models.A'>]
 >>> a2.delete()
 
+# Tests for nullable related fields
 
+>>> g = CollectedObjects()
+>>> g.add("key1", 1, "item1", None)
+False
+>>> g.add("key2", 1, "item1", "key1", nullable=True)
+False
+>>> g.add("key1", 1, "item1", "key2")
+True
+>>> g.ordered_keys()
+['key1', 'key2']
+
+>>> e1 = E()
+>>> e1.save()
+>>> f1 = F(e=e1)
+>>> f1.save()
+>>> e1.f = f1
+>>> e1.save()
+
+# Since E.f is nullable, we should delete F first (after nulling out
+# the E.f field), then E.
+
+>>> o = CollectedObjects()
+>>> e1._collect_sub_objects(o)
+>>> o.keys()
+[<class 'modeltests.delete.models.F'>, <class 'modeltests.delete.models.E'>]
+
+>>> e1.delete()
+
+>>> e2 = E()
+>>> e2.save()
+>>> f2 = F(e=e2)
+>>> f2.save()
+>>> e2.f = f2
+>>> e2.save()
+
+# Same deal as before, though we are starting from the other object.
+
+>>> o = CollectedObjects()
+>>> f2._collect_sub_objects(o)
+>>> o.keys()
+[<class 'modeltests.delete.models.F'>, <class 'modeltests.delete.models.E'>]
+
+>>> f2.delete()
 
 """
 }