django 保存数据时重写？

class Article(Model.model):
    title = ''
    title_hash = hash(title)

def save(self, *args, **kwargs):
    self.title_hash = hash(self.title)
    super(Article, self).save(*args, **kwargs)

def save_title_hash(self):
    title_hash = hash(title)
    return title_hash
title_hash = property(save_title_hash)