- tightened down conditions used to locate "relation direction", associating

  the "foreignkey" of the relationship with the "primaryjoin".  the column match now
  must be exact, not just "corresponding".  this enables self-referential relationships on a
  polymorphic mapper.
  - a little bit of improvement to the concept of a "concrete" inheritance mapping, though that concept
  is not well fleshed out yet (added test case to support concrete mappers on top of a polymorphic base).

4 files changed, 15 insertions, 5 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index 872f3d121..8efd70967 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -462,7 +462,7 @@ class Mapper(object):
 
         if self.inherits is not None:
             for key, prop in self.inherits.__props.iteritems():
-                if not self.__props.has_key(key):
+                if not self.__props.has_key(key) and (not self.concrete or not isinstance(prop, ColumnProperty)):
                     prop.adapt_to_inherited(key, self)
 
         # load properties from the main table object,
@@ -516,6 +516,8 @@ class Mapper(object):
         the columns of select_table should encompass all the columns of the mapped_table either directly
         or through proxying relationships."""
         if self.select_table is not self.mapped_table:
+            if self.polymorphic_identity is None:
+                raise exceptions.ArgumentError("Could not locate a polymorphic_identity field for mapper '%s'.  This field is required for polymorphic mappers" % str(self))
             props = {}
             if self.properties is not None:
                 for key, prop in self.properties.iteritems():
diff --git a/lib/sqlalchemy/orm/properties.py b/lib/sqlalchemy/orm/properties.py
index 452af04cc..db43a8e27 100644
--- a/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@ -274,8 +274,8 @@ class PropertyLoader(StrategizedProperty):
                 else:
                     return sync.MANYTOONE
         else:
-            onetomany = len([c for c in self.foreignkey if self.mapper.unjoined_table.corresponding_column(c, False) is not None])
-            manytoone = len([c for c in self.foreignkey if self.parent.unjoined_table.corresponding_column(c, False) is not None])
+            onetomany = len([c for c in self.foreignkey if self.mapper.unjoined_table.corresponding_column(c, False, require_exact=True) is not None])
+            manytoone = len([c for c in self.foreignkey if self.parent.unjoined_table.corresponding_column(c, False, require_exact=True) is not None])
             if not onetomany and not manytoone:
                 raise exceptions.ArgumentError("Cant determine relation direction for '%s' on mapper '%s' with primary join '%s' - foreign key columns are not present in neither the parent nor the child's mapped tables" %(self.key, str(self.parent), str(self.primaryjoin)))
             elif onetomany and manytoone:
diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py
index 54590f4ad..88a22bbcd 100644
--- a/lib/sqlalchemy/orm/strategies.py
+++ b/lib/sqlalchemy/orm/strategies.py
@@ -248,7 +248,7 @@ class LazyLoader(AbstractRelationLoader):
         binds = {}
         reverse = {}
         def column_in_table(table, column):
-            return table.corresponding_column(column, raiseerr=False, keys_ok=False) is not None
+            return table.corresponding_column(column, raiseerr=False, keys_ok=False, require_exact=True) is not None
 
         if remote_side is None or len(remote_side) == 0:
             remote_side = foreignkey
diff --git a/lib/sqlalchemy/sql.py b/lib/sqlalchemy/sql.py
index f944b468d..5b960546e 100644
--- a/lib/sqlalchemy/sql.py
+++ b/lib/sqlalchemy/sql.py
@@ -728,9 +728,17 @@ class FromClause(Selectable):
         if not hasattr(self, '_oid_column'):
             self._oid_column = self._locate_oid_column()
         return self._oid_column
-    def corresponding_column(self, column, raiseerr=True, keys_ok=False):
+    def corresponding_column(self, column, raiseerr=True, keys_ok=False, require_exact=False):
         """given a ColumnElement, return the ColumnElement object from this 
         Selectable which corresponds to that original Column via a proxy relationship."""
+        if require_exact:
+            if self.columns.get(column.key) is column:
+                return column
+            else:
+                if not raiseerr:
+                    return None
+                else:
+                    raise exceptions.InvalidRequestError("Column instance '%s' is not directly present in table '%s'" % (str(column), str(column.table)))
         for c in column.orig_set:
             try:
                 return self.original_columns[c]