1 files changed, 16 insertions, 0 deletions
diff --git a/lib/sqlalchemy/mapping/mapper.py b/lib/sqlalchemy/mapping/mapper.py
index 15d197a34..7977cae6a 100644
--- a/lib/sqlalchemy/mapping/mapper.py
+++ b/lib/sqlalchemy/mapping/mapper.py
@@ -450,6 +450,22 @@ class Mapper(object):
             self._options[optkey] = mapper
             return mapper
 
+    def _get_criterion(self, key, value):
+        """used by select_by to match a key/value pair against
+        local properties, column names, or a matching property in this mapper's
+        list of relations."""
+        if self.props.has_key(key):
+            return self.props[key].columns[0] == value
+        elif self.table.c.has_key(key):
+            return self.table.c[key] == value
+        else:
+            for prop in self.props.values():
+                c = prop.get_criterion(key, value)
+                if c is not None:
+                    return c
+            else:
+                return None
+
     def __getattr__(self, key):
         if (key.startswith('select_by_') or key.startswith('get_by_')):
             return getattr(self.query, key)