Fixed bug whereby joining a select() of a table "A" with multiple

foreign key paths to a table "B", to that table "B", would fail
to produce the "ambiguous join condition" error that would be
reported if you join table "A" directly to "B"; it would instead
produce a join condition with multiple criteria.
[ticket:2738]

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/sqlalchemy/schema.py b/lib/sqlalchemy/schema.py
index 3d59e8291..94df6751c 100644
--- a/lib/sqlalchemy/schema.py
+++ b/lib/sqlalchemy/schema.py
@@ -1134,7 +1134,8 @@ class Column(SchemaItem, expression.ColumnClause):
         information is not transferred.
 
         """
-        fk = [ForeignKey(f.column) for f in self.foreign_keys]
+        fk = [ForeignKey(f.column, _constraint=f.constraint)
+                for f in self.foreign_keys]
         if name is None and self.name is None:
             raise exc.InvalidRequestError("Cannot initialize a sub-selectable"
                     " with this Column object until it's 'name' has "