@classmethod
def commit(cls):
    """
        Call commit on the thread-local database transaction. "Begin" must be
        called to start a new transaction at this point, if a new transaction
        is desired.
        """
    if cls.app.local.sqla_tx is not None:
        cls.app.local.sqla_tx.commit()
        cls.app.local.sqla_tx = None
