backrefs on cyclical relationships were breaking for the "root" node which had None for a parent, due to addition in [changeset:1186] which added a "deletion" traversal for many-to-one relationships. added unittest.

2 files changed, 7 insertions, 0 deletions

diff --git a/lib/sqlalchemy/mapping/properties.py b/lib/sqlalchemy/mapping/properties.py
index 10d6472f4..b18d4d54f 100644
--- a/lib/sqlalchemy/mapping/properties.py
+++ b/lib/sqlalchemy/mapping/properties.py
@@ -382,6 +382,9 @@ class PropertyLoader(MapperProperty):
             else:
                 uowcommit.register_dependency(self.mapper, self.parent)
                 uowcommit.register_processor(self.mapper, self, self.parent, False)
+                # this dependency processor is used to locate "private" child objects
+                # during a "delete" operation, when the objectstore is being committed
+                # with only a partial list of objects
                 uowcommit.register_processor(self.mapper, self, self.parent, True)
         else:
             raise AssertionError(" no foreign key ?")
diff --git a/lib/sqlalchemy/mapping/unitofwork.py b/lib/sqlalchemy/mapping/unitofwork.py
index 0b392b447..1eea546df 100644
--- a/lib/sqlalchemy/mapping/unitofwork.py
+++ b/lib/sqlalchemy/mapping/unitofwork.py
@@ -647,6 +647,10 @@ class UOWTask(object):
                         childlist = childlist.added_items()
                         
                     for o in childlist:
+                        if o is None:
+                            # this can be None due to the many-to-one dependency processor added
+                            # for deleted items, line 385 properties.py
+                            continue
                         if not o in childtask.objects:
                             # item needs to be saved since its added, or attached to a deleted object
                             childtask.append(o, isdelete=isdelete and dep.processor.private)