- 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, 6 insertions, 9 deletions

diff --git a/lib/sqlalchemy/orm/loading.py b/lib/sqlalchemy/orm/loading.py
index a5d156a1f..4bd80c388 100644
--- a/lib/sqlalchemy/orm/loading.py
+++ b/lib/sqlalchemy/orm/loading.py
@@ -271,6 +271,7 @@ def instance_processor(mapper, context, path, adapter,
     new_populators = []
     existing_populators = []
     eager_populators = []
+
     load_path = context.query._current_path + path \
                 if context.query._current_path.path \
                 else path
@@ -504,9 +505,12 @@ def _populators(mapper, context, path, row, adapter,
     delayed_populators = []
     pops = (new_populators, existing_populators, delayed_populators,
                         eager_populators)
+
     for prop in mapper._props.itervalues():
+
         for i, pop in enumerate(prop.create_row_processor(
-                                    context, path,
+                                    context,
+                                    path,
                                     mapper, row, adapter)):
             if pop is not None:
                 pops[i].append((prop.key, pop))
@@ -529,17 +533,10 @@ def _configure_subclass_mapper(mapper, context, path, adapter):
         if sub_mapper is mapper:
             return None
 
-        # replace the tip of the path info with the subclass mapper
-        # being used, that way accurate "load_path" info is available
-        # for options invoked during deferred loads, e.g.
-        # query(Person).options(defer(Engineer.machines, Machine.name)).
-        # for AliasedClass paths, disregard this step (new in 0.8).
         return instance_processor(
                             sub_mapper,
                             context,
-                            path.parent[sub_mapper]
-                                if not path.is_aliased_class
-                                else path,
+                            path,
                             adapter,
                             polymorphic_from=mapper)
     return configure_subclass_mapper