Refactor to optionally load DatabasePushNotificationConfigStore

Author: kthota-g

src/a2a/server/tasks/__init__.py

@@ -5,9 +5,6 @@
 from a2a.server.tasks.base_push_notification_sender import (
     BasePushNotificationSender,
 )
-from a2a.server.tasks.database_push_notification_config_store import (
-    DatabasePushNotificationConfigStore,
-)
 from a2a.server.tasks.inmemory_push_notification_config_store import (
     InMemoryPushNotificationConfigStore,
 )
@@ -46,6 +43,28 @@ def __init__(self, *args, **kwargs):
             ) from _original_error
 
 
+try:
+    from a2a.server.tasks.database_push_notification_config_store import (
+        DatabasePushNotificationConfigStore,  # type: ignore
+    )
+except ImportError as e:
+    _original_error = e
+    # If the database push notification config store is not available, we can still use in-memory stores.
+    logger.debug(
+        'DatabasePushNotificationConfigStore not loaded. This is expected if database dependencies are not installed. Error: %s',
+        e,
+    )
+
+    class DatabasePushNotificationConfigStore:  # type: ignore
+        """Placeholder for DatabasePushNotificationConfigStore when dependencies are not installed."""
+
+        def __init__(self, *args, **kwargs):
+            raise ImportError(
+                'To use DatabasePushNotificationConfigStore, its dependencies must be installed. '
+                'You can install them with \'pip install "a2a-sdk[sql]"\''
+            ) from _original_error
+
+
 __all__ = [
     'BasePushNotificationSender',
     'DatabasePushNotificationConfigStore',