- some naming changes on PropComparator, Comparator:

  1. all Comparators now have "parent" which is always the parent mapper
  or AliasedClass instance

  2. only RelationshipProperty.Comparator has "mapper" now, which
  is the target mapper

  3. The names "parententity" and "parentmapper" are underscored

also improved the message with the "neither comparator nor instruentedattribute...."
to include the classname + attribute name

1 files changed, 14 insertions, 5 deletions

diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index 86da9a61d..7effd8e58 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -131,7 +131,7 @@ class QueryableAttribute(interfaces._MappedAttribute,
         self.key = key
         self.impl = impl
         self.comparator = comparator
-        self.parententity = parententity
+        self._parententity = parententity
         self._of_type = of_type
 
         manager = manager_of_class(class_)
@@ -159,6 +159,10 @@ class QueryableAttribute(interfaces._MappedAttribute,
         return self
 
     @property
+    def parent(self):
+        return self._parententity
+
+    @property
     def expression(self):
         return self.comparator.__clause_element__()
 
@@ -171,7 +175,7 @@ class QueryableAttribute(interfaces._MappedAttribute,
                     self.key,
                     self.impl,
                     self.comparator.of_type(cls),
-                    self.parententity,
+                    self._parententity,
                     of_type=cls)
 
     def label(self, name):
@@ -191,9 +195,11 @@ class QueryableAttribute(interfaces._MappedAttribute,
             return getattr(self.comparator, key)
         except AttributeError:
             raise AttributeError(
-                    'Neither %r object nor %r object has an attribute %r' % (
+                    'Neither %r object nor %r object associated with %s '
+                    'has an attribute %r' % (
                     type(self).__name__,
                     type(self.comparator).__name__,
+                    self,
                     key)
             )
 
@@ -281,7 +287,7 @@ def create_proxied_attribute(descriptor):
                 return self.descriptor.__get__(instance, owner)
 
         def __str__(self):
-            return self.key
+            return "%s.%s" % (self.class_.__name__, self.key)
 
         def __getattr__(self, attribute):
             """Delegate __getattr__ to the original descriptor and/or
@@ -294,12 +300,15 @@ def create_proxied_attribute(descriptor):
                     return getattr(self.comparator, attribute)
                 except AttributeError:
                     raise AttributeError(
-                    'Neither %r object nor %r object has an attribute %r' % (
+                    'Neither %r object nor %r object associated with %s '
+                    'has an attribute %r' % (
                     type(descriptor).__name__,
                     type(self.comparator).__name__,
+                    self,
                     attribute)
                     )
 
+
     Proxy.__name__ = type(descriptor).__name__ + 'Proxy'
 
     util.monkeypatch_proxied_specials(Proxy, type(descriptor),