Fix ambiguous column sorting

sqlalchemy_utils/functions/orm.py

@@ -508,10 +508,11 @@ def get_all_descriptors(expr):
     insp = sa.inspect(expr)
     polymorphic_mappers = get_polymorphic_mappers(insp)
     if polymorphic_mappers:
-
-        attrs = {}
+        attrs = dict(get_mapper(expr).all_orm_descriptors)
         for submapper in polymorphic_mappers:
-            attrs.update(submapper.all_orm_descriptors)
+            for key, descriptor in submapper.all_orm_descriptors.items():
+                if key not in attrs:
+                    attrs[key] = descriptor
         return attrs
     return get_mapper(expr).all_orm_descriptors
 

tests/test_sort_query.py

@@ -273,6 +273,13 @@ class TestSortQueryWithPolymorphicInheritance(TestCase):
         )
         assert_contains('ORDER BY article.category ASC', query)
 
+    def test_with_ambiguous_column(self):
+        query = sort_query(
+            self.session.query(self.TextItem),
+            'id'
+        )
+        assert_contains('ORDER BY text_item.id ASC', query)
+
 
 class TestSortQueryWithCustomPolymorphic(TestCase):
     """