- A new construct :class:`.Bundle` is added, which allows for specification

of groups of column expressions to a :class:`.Query` construct.
The group of columns are returned as a single tuple by default.  The
behavior of :class:`.Bundle` can be overridden however to provide
any sort of result processing to the returned row.  One example included
is :attr:`.Composite.Comparator.bundle`, which applies a bundled form
of a "composite" mapped attribute.
[ticket:2824]
- The :func:`.composite` construct now maintains the return object
when used in a column-oriented :class:`.Query`, rather than expanding
out into individual columns.  This makes use of the new :class:`.Bundle`
feature internally.  This behavior is backwards incompatible; to
select from a composite column which will expand out, use
``MyClass.some_composite.clauses``.

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index 949eafca4..da9d62d13 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -143,6 +143,12 @@ class QueryableAttribute(interfaces._MappedAttribute,
     def __clause_element__(self):
         return self.comparator.__clause_element__()
 
+    def _query_clause_element(self):
+        """like __clause_element__(), but called specifically
+        by :class:`.Query` to allow special behavior."""
+
+        return self.comparator._query_clause_element()
+
     def of_type(self, cls):
         return QueryableAttribute(
                     self.class_,
@@ -153,7 +159,7 @@ class QueryableAttribute(interfaces._MappedAttribute,
                     of_type=cls)
 
     def label(self, name):
-        return self.__clause_element__().label(name)
+        return self._query_clause_element().label(name)
 
     def operate(self, op, *other, **kwargs):
         return op(self.comparator, *other, **kwargs)