Fixed #9308 -- Corrected the updated of nullable foreign key fields w…

…hen deleting objects. Thanks to Bob Thomas for the fix, and markshep for the improvements on the test case.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10822 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/query.py

@@ -615,7 +615,7 @@ def only(self, *fields):
         clone = self._clone()
         clone.query.add_immediate_loading(fields)
         return clone
-        
+
     ###################################
     # PUBLIC INTROSPECTION ATTRIBUTES #
     ###################################
@@ -632,7 +632,7 @@ def ordered(self):
         else:
             return False
     ordered = property(ordered)
-    
+
     ###################
     # PRIVATE METHODS #
     ###################
@@ -1007,7 +1007,7 @@ 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 @@ class F(DefaultRepr, models.Model):
 
 >>> 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 @@ class F(DefaultRepr, models.Model):
 >>> 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 @@ class F(DefaultRepr, models.Model):
 [<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
 """
 }