fix scalar_subquery warnings

sqlalchemy_utils/aggregates.py

@@ -369,6 +369,7 @@ class Rating(Base):
 from sqlalchemy.ext.declarative import declared_attr
 from sqlalchemy.sql.functions import _FunctionGenerator
 
+from .compat import get_scalar_subquery
 from .functions.orm import get_column_key
 from .relationships import (
     chained_join,
@@ -452,7 +453,7 @@ def aggregate_query(self):
             self.relationships[0].mapper.class_
         )
 
-        return query.as_scalar()
+        return get_scalar_subquery(query)
 
     def update_query(self, objects):
         table = self.class_.__table__

sqlalchemy_utils/compat.py

@@ -0,0 +1,5 @@
+def get_scalar_subquery(query):
+    try:
+        return query.scalar_subquery()
+    except AttributeError:
+        return query.as_scalar()

tests/functions/test_cast_if.py

@@ -3,6 +3,7 @@
 from sqlalchemy.ext.declarative import declarative_base
 
 from sqlalchemy_utils import cast_if
+from sqlalchemy_utils.compat import get_scalar_subquery
 
 
 @pytest.fixture(scope='class')
@@ -39,7 +40,7 @@ def test_synonym(self, article_cls):
         assert cast_if(expr, sa.String) is expr
 
     def test_scalar_selectable(self, article_cls):
-        expr = sa.select([article_cls.id]).as_scalar()
+        expr = get_scalar_subquery(sa.select([article_cls.id]))
         assert cast_if(expr, sa.Integer) is expr
 
     def test_scalar(self):

tests/functions/test_get_type.py

@@ -2,6 +2,7 @@
 import sqlalchemy as sa
 
 from sqlalchemy_utils import get_type
+from sqlalchemy_utils.compat import get_scalar_subquery
 
 
 @pytest.fixture
@@ -45,5 +46,5 @@ def test_relationship_property(self, Article, User):
         assert get_type(Article.author) == User
 
     def test_scalar_select(self, Article):
-        query = sa.select([Article.id]).as_scalar()
+        query = get_scalar_subquery(sa.select([Article.id]))
         assert isinstance(get_type(query), sa.Integer)

tests/types/test_int_range.py

@@ -2,6 +2,7 @@
 import sqlalchemy as sa
 
 from sqlalchemy_utils import IntRangeType
+from sqlalchemy_utils.compat import get_scalar_subquery
 
 intervals = None
 inf = -1
@@ -283,7 +284,7 @@ def test_eq_with_query_arg(self, session, Building, create_building):
             session.query(Building)
             .filter(
                 Building.persons_at_night ==
-                session.query(Building.persons_at_night)
+                get_scalar_subquery(session.query(Building.persons_at_night))
             ).order_by(Building.persons_at_night).limit(1)
         )
         assert query.count()