- refactor of pathing mechanics, to address #2614, #2617

- paths now store Mapper + MapperProperty now instead of string key,
so that the parent mapper for the property is known, supports same-named
properties on multiple subclasses
- the Mapper within the path is now always relevant to the property
to the right of it.  PathRegistry does the translation now, instead
of having all the outside users of PathRegistry worry about it,
to produce a path that is much more consistent.  Paths are now
consistent with mappings in all cases.  Special logic to get at
"with_polymorphic" structures and such added also.
- AliasedClass now has two modes, "use_mapper_path" and regular;
"use_mapper_path" is for all those situations where we put an AliasedClass
in for a plain class internally, and want it to "path" with the
plain mapper.
- The AliasedInsp is now the first class "entity" for an AliasedClass,
and is passed around internally and used as attr._parententity
and such.  it is the AliasedClass analogue for Mapper.

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index b89163340..626105b5e 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -472,7 +472,7 @@ class Mapper(_InspectionAttr):
     dispatch = event.dispatcher(events.MapperEvents)
 
     @util.memoized_property
-    def _sa_path_registry(self):
+    def _path_registry(self):
         return PathRegistry.per_mapper(self)
 
     def _configure_inheritance(self):
@@ -1403,7 +1403,7 @@ class Mapper(_InspectionAttr):
         if _new_mappers:
             configure_mappers()
         if not self.with_polymorphic:
-            return [self]
+            return []
         return self._mappers_from_spec(*self.with_polymorphic)
 
     @_memoized_configured_property
@@ -1458,10 +1458,10 @@ class Mapper(_InspectionAttr):
         return list(self._iterate_polymorphic_properties(
             self._with_polymorphic_mappers))
 
+
     def _iterate_polymorphic_properties(self, mappers=None):
         """Return an iterator of MapperProperty objects which will render into
         a SELECT."""
-
         if mappers is None:
             mappers = self._with_polymorphic_mappers