def get_last_tid(self):
        try:
            spec = {'tid': {'$gt': 0}}
            sort = [('tid', -1)]
            row = self.db.docs.find_one(spec, sort=sort)
        except Exception as e:
            raise DatabaseException(e)
        if row:
            return row['tid']
        return 0
def unique_name():
    now_time = datetime.datetime.now().strftime("%Y%m%d%H%M%S")
    random_num = random.randint(0, 100)
    if random_num <= 10:
        random_num = str(0) + str(random_num)
    unique_num = str(now_time) + str(random_num)
    return unique_num