Small improvement on FlushError can't delete error messagepr/148

Output in the error message the table name and the column name.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/persistence.py b/lib/sqlalchemy/orm/persistence.py
index 114b79ea5..28254cc10 100644
--- a/lib/sqlalchemy/orm/persistence.py
+++ b/lib/sqlalchemy/orm/persistence.py
@@ -441,9 +441,9 @@ def _collect_delete_commands(base_mapper, uowtransaction, table,
                     state, state_dict, col)
             if value is None:
                 raise orm_exc.FlushError(
-                    "Can't delete from table "
+                    "Can't delete from table %s "
                     "using NULL for primary "
-                    "key value")
+                    "key value on column %s" % (table, col))
 
         if update_version_id is not None and \
                 table.c.contains_column(mapper.version_id_col):