不能通过它的id读取AppEngine ndb模型

Question

我要插入以下代码，然后按键读取实体。但是我总是得到无。我可以发誓，这是我以前在旧版AppEngine中完成它的方式...

    guid = uuid.uuid1().hex

    a = User(id=guid)
    a.email = "a"
    a.username = "a"
    a.put()

    logging.info("a.key: %s", a.key)

    theKey = ndb.Key(User, guid)

    entity1 = theKey.get()          #doesnt work
    entity2 = User.get_by_id(guid)  #doesnt work

    logging.info("guid: %s", guid)
    logging.info("key: %s", keyValue)
    logging.info("entities: %s %s" % (entity1, entity2))