Add support for InstrumentedAttributes in get_mapper

sqlalchemy_utils/functions/orm.py

@@ -83,6 +83,8 @@ def get_mapper(mixed):
         mixed = mixed.element
     if isinstance(mixed, AliasedInsp):
         return mixed.mapper
+    if isinstance(mixed, sa.orm.attributes.InstrumentedAttribute):
+        mixed = mixed.class_
     if isinstance(mixed, sa.Table):
         mappers = [
             mapper for mapper in mapperlib._mapper_registry

tests/functions/test_get_mapper.py

@@ -42,6 +42,11 @@ class TestGetMapper(object):
             sa.inspect(self.Building)
         )
 
+    def test_instrumented_attribute(self):
+        assert (
+            get_mapper(self.Building.id) == sa.inspect(self.Building)
+        )
+
     def test_table_alias(self):
         alias = sa.orm.aliased(self.Building.__table__)
         assert (