code: def sync(self):
          
          if self.wechat_id is not None:
  
              res = self.client.find_one({'wechat_id': self.wechat_id})
          else:
              res = self.client.find_one(
                  {
                      'username': self.username,
                      'password': self.password
                  }
              )
          if res is None:
  
              if self.client.find_one({'username': self.username}) is None:
                  self.client.insert_one(self.message)
                  return self
              else:
                  raise RuntimeError('账户名已存在且账户密码不匹配')
  
          else:
              self.reload(res)
  
              return self
docs: 基于账户/密码去sync数据库