- Fixed ORM bug where the :func:`.class_mapper` function would mask

AttributeErrors or KeyErrors that should raise during mapper
configuration due to user errors.  The catch for attribute/keyerror
has been made more specific to not include the configuration step.
fixes #3047

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/base.py b/lib/sqlalchemy/orm/base.py
index e973de897..e81375787 100644
--- a/lib/sqlalchemy/orm/base.py
+++ b/lib/sqlalchemy/orm/base.py
@@ -351,12 +351,13 @@ def _inspect_mapped_class(class_, configure=False):
         if not class_manager.is_mapped:
             return None
         mapper = class_manager.mapper
+    except exc.NO_STATE:
+        return None
+    else:
         if configure and mapper._new_mappers:
             mapper._configure_all()
         return mapper
 
-    except exc.NO_STATE:
-        return None
 
 def class_mapper(class_, configure=True):
     """Given a class, return the primary :class:`.Mapper` associated