- fix to cascades on polymorphic relations, such that cascades

from an object to a polymorphic collection continue cascading
along the set of attributes specific to each element in the collection.

2 files changed, 8 insertions, 5 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index 0f5dbaaf5..e9fe41fdc 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -1538,8 +1538,8 @@ def has_mapper(object):
 
     return hasattr(object, '_entity_name')
 
-def _state_mapper(state):
-    return state.class_._class_state.mappers[state.dict.get('_entity_name', None)]
+def _state_mapper(state, entity_name=None):
+    return state.class_._class_state.mappers[state.dict.get('_entity_name', entity_name)]
 
 def object_mapper(object, entity_name=None, raiseerror=True):
     """Given an object, return the primary Mapper associated with the object instance.
diff --git a/lib/sqlalchemy/orm/properties.py b/lib/sqlalchemy/orm/properties.py
index 9394e9aea..4d41556a0 100644
--- a/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@ -13,7 +13,7 @@ to handle flush-time dependency sorting and processing.
 
 from sqlalchemy import sql, schema, util, exceptions, logging
 from sqlalchemy.sql import util as sql_util, visitors, operators, ColumnElement
-from sqlalchemy.orm import mapper, sync, strategies, attributes, dependency
+from sqlalchemy.orm import mapper, sync, strategies, attributes, dependency, object_mapper
 from sqlalchemy.orm import session as sessionlib
 from sqlalchemy.orm import util as mapperutil
 from sqlalchemy.orm.interfaces import StrategizedProperty, PropComparator, MapperProperty
@@ -365,8 +365,11 @@ class PropertyLoader(StrategizedProperty):
                     if not isinstance(c, self.mapper.class_):
                         raise exceptions.AssertionError("Attribute '%s' on class '%s' doesn't handle objects of type '%s'" % (self.key, str(self.parent.class_), str(c.__class__)))
                     recursive.add(c)
-                    yield (c, mapper)
-                    for (c2, m) in mapper.cascade_iterator(type, c._state, recursive):
+
+                    # cascade using the mapper local to this object, so that its individual properties are located
+                    instance_mapper = object_mapper(c, entity_name=mapper.entity_name)  
+                    yield (c, instance_mapper)
+                    for (c2, m) in instance_mapper.cascade_iterator(type, c._state, recursive):
                         yield (c2, m)
 
     def _get_target_class(self):