if an object fails construction, doesnt get added to the session

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index 90db7f83e..ac8d6f330 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -468,7 +468,12 @@ class Mapper(object):
                 session._register_new(self)
 
             if oldinit is not None:
-                oldinit(self, *args, **kwargs)
+                try:
+                    oldinit(self, *args, **kwargs)
+                except:
+                    if session is not None:
+                        session.expunge(self)
+                    raise
         # override oldinit, insuring that its not already a Mapper-decorated init method
         if oldinit is None or not hasattr(oldinit, '_sa_mapper_init'):
             init._sa_mapper_init = True