def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def deserialize(self, value, display=False):
        value = decode(value).strip()
        validators.validate_required(value, self._required)
        if not value:
            return None

        socket_path = path.get_unix_socket_path(value)
        if socket_path is not None:
            path_str = Path(not self._required).deserialize(socket_path)
            return f"unix:{path_str}"

        try:
            socket.getaddrinfo(value, None)
        except OSError:
            raise ValueError("must be a resolveable hostname or valid IP")

        return value