Add Query.enable_single_entity()

Added new feature :meth:`.Query.only_return_tuples`.  Causes the
:class:`.Query` object to return keyed tuple objects unconditionally even
if the query is against a single entity.   Pull request courtesy Eric
Atkin.

Change-Id: Ib0b7f5f78431aa68082e5b200ed577daa4222336
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/425

2 files changed, 13 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/loading.py b/lib/sqlalchemy/orm/loading.py
index 2628093e0..3599aa3e7 100644
--- a/lib/sqlalchemy/orm/loading.py
+++ b/lib/sqlalchemy/orm/loading.py
@@ -37,7 +37,8 @@ def instances(query, cursor, context):
 
     filtered = query._has_mapper_entities
 
-    single_entity = len(query._entities) == 1 and \
+    single_entity = not query._only_return_tuples and \
+        len(query._entities) == 1 and \
         query._entities[0].supports_single_entity
 
     if filtered:
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index 1e7f8a266..043be5539 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -70,6 +70,7 @@ class Query(object):
 
     """
 
+    _only_return_tuples = False
     _enable_eagerloads = True
     _enable_assertions = True
     _with_labels = False
@@ -604,6 +605,16 @@ class Query(object):
         return self.enable_eagerloads(False).with_labels().statement
 
     @_generative()
+    def only_return_tuples(self, value):
+        """When set to True, the query results will always be a tuple,
+        specifically for single element queries. The default is False.
+
+    .   .. versionadded:: 1.2.5
+
+        """
+        self._only_return_tuples = value
+
+    @_generative()
     def enable_eagerloads(self, value):
         """Control whether or not eager joins and subqueries are
         rendered.