def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
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