- Fixed bug which is actually a regression that occurred between

versions 0.8.0 and 0.8.1, due :ticket:`2714`.  The case where
joined eager loading needs to join out over a subclass-bound
relationship when "with_polymorphic" were also used would fail
to join from the correct entity.
fixes #3593

2 files changed, 15 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py
index 7de470dd5..21152e304 100644
--- a/lib/sqlalchemy/orm/strategies.py
+++ b/lib/sqlalchemy/orm/strategies.py
@@ -1325,8 +1325,17 @@ class JoinedLoader(AbstractRelationshipLoader):
 
         if adapter:
             if getattr(adapter, 'aliased_class', None):
+                # joining from an adapted entity.  The adapted entity
+                # might be a "with_polymorphic", so resolve that to our
+                # specific mapper's entity before looking for our attribute
+                # name on it.
+                efm = inspect(adapter.aliased_class).\
+                    _entity_for_mapper(self.parent)
+
+                # look for our attribute on the adapted entity, else fall back
+                # to our straight property
                 onclause = getattr(
-                    adapter.aliased_class, self.key,
+                    efm.entity, self.key,
                     self.parent_property)
             else:
                 onclause = getattr(
diff --git a/lib/sqlalchemy/orm/util.py b/lib/sqlalchemy/orm/util.py
index 4351c8dc6..46183a47d 100644
--- a/lib/sqlalchemy/orm/util.py
+++ b/lib/sqlalchemy/orm/util.py
@@ -537,7 +537,11 @@ class AliasedInsp(InspectionAttr):
     def _entity_for_mapper(self, mapper):
         self_poly = self.with_polymorphic_mappers
         if mapper in self_poly:
-            return getattr(self.entity, mapper.class_.__name__)._aliased_insp
+            if mapper is self.mapper:
+                return self
+            else:
+                return getattr(
+                    self.entity, mapper.class_.__name__)._aliased_insp
         elif mapper.isa(self.mapper):
             return self
         else: