我正在设置一个 Ladon SOAP 服务器,但根本无法让它返回列表。
这是我所拥有的:
class V1(object):
    """
    This service returns events between two times for a given trackable.
    """
    @ladonize(rtype=[ PORTABLE_STRING ])
    def getGroupNames(self):
        """
        Returns a list of group names.
        @rtype: List of group names.
        """
        cnn = db.get_connection()
        sql = "blah blah sql"
        params = {}
        groups = db.execute_fetchall(cnn, sql, params)
        ret = []
        for g in groups:
            ret += [g["group_description"]]
        return ret
我得到的错误是:
WebFault: Server raised fault: 'Return-type mismatch in V1::getGroupNames: Expected [<type 'unicode'>] recieved <type 'list'>'
它需要一个 unicode 列表,而我正在返回一个 unicode 列表,但它坚持认为它们不是一回事。
我错过了什么?