- Improved the determination of the FROM clause

when placing SQL expressions in the query()
list of entities.  In particular scalar subqueries
should not "leak" their inner FROM objects out
into the enclosing query.

CHANGES

@@ -16,6 +16,12 @@ CHANGES
       Column objects such as Query(table.c.col) will
       return the "key" attribute of the Column.
 
+    - Improved the determination of the FROM clause
+      when placing SQL expressions in the query()
+      list of entities.  In particular scalar subqueries
+      should not "leak" their inner FROM objects out
+      into the enclosing query.
+      
 - sql
     - Temporarily rolled back the "ORDER BY" enhancement
       from [ticket:1068].  This feature is on hold 

lib/sqlalchemy/orm/query.py

@@ -1625,11 +1625,22 @@ class _ColumnEntity(_QueryEntity):
 
         self.column = column
         self.froms = set()
+        
+        # look for ORM entities represented within the
+        # given expression.  Try to count only entities 
+        # for columns whos FROM object is in the actual list
+        # of FROMs for the overall expression - this helps
+        # subqueries which were built from ORM constructs from
+        # leaking out their entities into the main select construct
+        actual_froms = set(column._get_from_objects())
+
         self.entities = util.OrderedSet(
             elem._annotations['parententity']
             for elem in visitors.iterate(column, {})
-            if 'parententity' in elem._annotations)
-        
+            if 'parententity' in elem._annotations
+            and actual_froms.intersection(elem._get_from_objects())
+            )
+            
         if self.entities:
             self.entity_zero = list(self.entities)[0]
         else:

test/orm/inheritance/query.py

@@ -510,7 +510,6 @@ def make_test(select_type):
             
             self.assertEquals(sess.query(Person).filter(Person.person_id==subq).one(), e1)
             
-        
         def test_mixed_entities(self):
             sess = create_session()
 
@@ -537,7 +536,6 @@ def make_test(select_type):
                 [('pointy haired boss foo', ), ('dogbert foo',)]
             )
 
-
             row = sess.query(Engineer.name, Engineer.primary_language).filter(Engineer.name=='dilbert').first()
             assert row.name == 'dilbert'
             assert row.primary_language == 'java'

test/orm/query.py

@@ -1207,6 +1207,36 @@ class MixedEntitiesTest(QueryTest):
         q2 = q.select_from(sel).filter(users.c.id==8).filter(users.c.id>sel.c.id).values(users.c.name, sel.c.name, User.name)
         self.assertEquals(list(q2), [(u'ed', u'jack', u'jack')])
     
+    def test_scalar_subquery(self):
+        """test that a subquery constructed from ORM attributes doesn't leak out 
+        those entities to the outermost query.
+        
+        """
+        sess = create_session()
+        
+        subq = select([func.count()]).\
+            where(User.id==Address.user_id).\
+            correlate(users).\
+            label('count')
+
+        # we don't want Address to be outside of the subquery here
+        self.assertEquals(
+            list(sess.query(User, subq)[0:3]),
+            [(User(id=7,name=u'jack'), 1), (User(id=8,name=u'ed'), 3), (User(id=9,name=u'fred'), 1)]
+            )
+
+        # same thing without the correlate, as it should
+        # not be needed
+        subq = select([func.count()]).\
+            where(User.id==Address.user_id).\
+            label('count')
+
+        # we don't want Address to be outside of the subquery here
+        self.assertEquals(
+            list(sess.query(User, subq)[0:3]),
+            [(User(id=7,name=u'jack'), 1), (User(id=8,name=u'ed'), 3), (User(id=9,name=u'fred'), 1)]
+            )
+    
     def test_tuple_labeling(self):
         sess = create_session()
         for row in sess.query(User, Address).join(User.addresses).all():