appengine.py 文件源码

def _is_ndb(self):
    """Determine whether the model of the instance is an NDB model.

    Returns:
      Boolean indicating whether or not the model is an NDB or DB model.
    """
    # issubclass will fail if one of the arguments is not a class, only need
    # worry about new-style classes since ndb and db models are new-style
    if isinstance(self._model, type):
      if ndb is not None and issubclass(self._model, ndb.Model):
        return True
      elif issubclass(self._model, db.Model):
        return False

    raise TypeError('Model class not an NDB or DB model: %s.' % (self._model,))