Added better relationship property handling

sqlalchemy_utils/functions/sort_query.py

@@ -94,7 +94,9 @@ class QuerySorter(object):
                     expr = property_.columns[0].name
                 else:
                     expr = sort_expression(entity, property_.key)
-            return expr
+                return expr
+            else:
+                return
 
         if isinstance(entity, AliasedInsp):
             entity = entity.entity

tests/test_sort_query.py

@@ -109,6 +109,11 @@ class TestSortQuery(TestCase):
         sorted_query = sort_query(query, '-article_count')
         assert 'article_count DESC' in str(sorted_query)
 
+    def test_relationship_property(self):
+        query = self.session.query(self.Category)
+        query = sort_query(query, 'articles')
+        assert 'ORDER BY' not in str(query)
+
     def test_hybrid_property(self):
         query = self.session.query(self.Category)
         query = sort_query(query, 'articles_count')