alter where bool cast is

airflow/utils/db.py

@@ -1458,7 +1458,8 @@ def check_query_exists(query_stmt: Select, *, session: Session) -> bool:
     :meta private:
     """
     count_stmt = select(literal(True)).select_from(query_stmt.order_by(None).subquery())
-    return session.scalar(count_stmt)
+    # we must cast to bool because scalar() can return None
+    return bool(session.scalar(count_stmt))
 
 
 def exists_query(*where: ClauseElement, session: Session) -> bool:
@@ -1557,9 +1558,7 @@ def __setstate__(self, state: Any) -> None:
         self._session = get_current_task_instance_session()
 
     def __bool__(self) -> bool:
-        if check := check_query_exists(self._select_asc, session=self._session) is not None:
-            return check
-        return False
+        return check_query_exists(self._select_asc, session=self._session)
 
     def __eq__(self, other: Any) -> bool:
         if not isinstance(other, collections.abc.Sequence):

tests/utils/test_db.py

@@ -37,6 +37,7 @@
 from airflow.models import Base as airflow_base
 from airflow.settings import engine
 from airflow.utils.db import (
+    LazySelectSequence,
     _get_alembic_config,
     check_migrations,
     compare_server_default,
@@ -56,6 +57,12 @@
 pytestmark = [pytest.mark.db_test, pytest.mark.skip_if_database_isolation_mode]
 
 
+class EmptyLazySelectSequence(LazySelectSequence):
+    _data = []
+
+    def __init__(self):
+        super().__init__(None, None, session="MockSession")
+
 class TestDb:
     def test_database_schema_and_sqlalchemy_model_are_in_sync(self):
         import airflow.models
@@ -251,3 +258,10 @@ def test_alembic_configuration(self):
         import airflow
 
         assert config.config_file_name == os.path.join(os.path.dirname(airflow.__file__), "alembic.ini")
+
+    @mock.patch("sqlalchemy.orm.Session.scalar")
+    def test_bool_lazy_select_sequence(self, mock_scalar):
+        mock_scalar.return_value = None
+
+        lss = EmptyLazySelectSequence()
+        assert not bool(lss)