- Fixed bug in baked loader system where the systemwide monkeypatch

for setting up baked lazy loaders would interfere with other
loader strategies that rely on lazy loading as a fallback, e.g.
joined and subquery eager loaders, leading to ``IndexError``
exceptions at mapper configuration time.
fixes #3612

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/interfaces.py b/lib/sqlalchemy/orm/interfaces.py
index ed8f27332..e9ad75e31 100644
--- a/lib/sqlalchemy/orm/interfaces.py
+++ b/lib/sqlalchemy/orm/interfaces.py
@@ -493,7 +493,11 @@ class StrategizedProperty(MapperProperty):
             return strategy
 
     def _get_strategy_by_cls(self, cls):
-        return self._get_strategy(cls._strategy_keys[0])
+        try:
+            return self._get_strategy(cls._strategy_keys[0])
+        except IndexError:
+            import pdb
+            pdb.set_trace()
 
     def setup(
             self, context, entity, path, adapter, **kwargs):