- fixed bug with session.dirty when using "mutable scalars"

(such as PickleTypes)

- added a more descriptive error message when flushing on a
relation() that has non-locally-mapped columns in its primary or
secondary join condition

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/sqlalchemy/exceptions.py b/lib/sqlalchemy/exceptions.py
index 8dbbb91c8..02cee5063 100644
--- a/lib/sqlalchemy/exceptions.py
+++ b/lib/sqlalchemy/exceptions.py
@@ -46,7 +46,10 @@ class InvalidRequestError(SQLAlchemyError):
     This error generally corresponds to runtime state errors.
     """
 
-
+class UnmappedColumnError(InvalidRequestError):
+    """A mapper was asked to return mapped information about a column 
+    which it does not map"""
+    
 class NoSuchTableError(InvalidRequestError):
     """SQLAlchemy was asked to load a table's definition from the
     database, but the table doesn't exist.