Django模型实例的递归函数

我想让消息视图显示导致该消息的所有其他消息。原始消息对值没有响应,应终止递归。有更好的方法吗?(我关注的是内存过快,因为线程的长度一般不应超过10-20条消息)。

def get_thread(msg,msg_set=[]):
    """
    This will get all the messages that led up to any particular message
    it takes only a message, but if the message isn't the first message
    in a thread it appends it to a message list to be returned.

    the last message in the list should be the first message created
    """
    if msg.response_to:
        return get_thread(msg.response_to, msg_set+[msg])
    return msg_set+[msg]


# Create your models here.
class Message(models.Model):
    body = models.TextField()
    sender = models.ForeignKey(User,related_name='sender')
    recipients = models.ManyToManyField(User,related_name='recipients')
    timestamp = models.DateTimeField(default=datetime.datetime.now)
    response_to = models.ForeignKey(Message,related_name='response_to')

    def thread(self):
        return get_thread(self)