[1.0.X] Fixed #9308 -- Corrected the updated of nullable foreign key fields when deleting objects. Thanks to Bob Thomas for the fix, and markshep for the improvements on the test case.

Merge of r10822 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@10823 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/query.py

@@ -867,7 +867,7 @@ def delete_objects(seen_objs):
         update_query = sql.UpdateQuery(cls, connection)
         for field, model in cls._meta.get_fields_with_model():
             if (field.rel and field.null and field.rel.to in seen_objs and
-                    filter(lambda f: f.column == field.column,
+                    filter(lambda f: f.column == field.rel.get_related_field().column,
                     field.rel.to._meta.fields)):
                 if model:
                     sql.UpdateQuery(model, connection).clear_related(field,

tests/modeltests/delete/models.py

@@ -30,7 +30,7 @@ class D(DefaultRepr, models.Model):
 # D -> A
 
 # So, we must delete Ds first of all, then Cs then Bs then As.
-# However, if we start at As, we might find Bs first (in which 
+# 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
@@ -96,7 +96,7 @@ CyclicDependency: There is a cyclic dependency of items to be processed.
 
 >>> def clear_rel_obj_caches(models):
 ...     for m in models:
-...         if hasattr(m._meta, '_related_objects_cache'): 
+...         if hasattr(m._meta, '_related_objects_cache'):
 ...             del m._meta._related_objects_cache
 
 # Nice order
@@ -168,7 +168,16 @@ True
 >>> o.keys()
 [<class 'modeltests.delete.models.F'>, <class 'modeltests.delete.models.E'>]
 
+# temporarily replace the UpdateQuery class to verify that E.f is actually nulled out first
+>>> import django.db.models.sql
+>>> class LoggingUpdateQuery(django.db.models.sql.UpdateQuery):
+...     def clear_related(self, related_field, pk_list):
+...         print "CLEARING FIELD",related_field.name
+...         return super(LoggingUpdateQuery, self).clear_related(related_field, pk_list)
+>>> original_class = django.db.models.sql.UpdateQuery
+>>> django.db.models.sql.UpdateQuery = LoggingUpdateQuery
 >>> e1.delete()
+CLEARING FIELD f
 
 >>> e2 = E()
 >>> e2.save()
@@ -185,6 +194,9 @@ True
 [<class 'modeltests.delete.models.F'>, <class 'modeltests.delete.models.E'>]
 
 >>> f2.delete()
+CLEARING FIELD f
 
+# Put this back to normal
+>>> django.db.models.sql.UpdateQuery = original_class
 """
 }