metadata.py 文件源码

def key_for_entity(cls, entity_or_key):
    """Return the metadata key for the entity group containing entity_or_key.

    Use this key to get() the __entity_group__ metadata entity for the
    entity group containing entity_or_key.

    Args:
      entity_or_key: a key or entity whose __entity_group__ key you want.

    Returns:
      The __entity_group__ key for the entity group containing entity_or_key.
    """
    if isinstance(entity_or_key, db.Model):
      key = entity_or_key.key()
    else:
      key = entity_or_key
    while key.parent():
      key = key.parent()
    return db.Key.from_path(cls.KIND_NAME, cls.ID, parent=key)