Javascript 更新StackMob用户对象JS-SDK

我正在尝试使用JS-SDK更新用户对象，但我得到了模式错误的重复密钥。使用StackMob JS-SDK更新用户对象的正确方法是什么？下面是我的代码

var Usr = StackMob.Model.extend({schemaName: 'user'});
var rid = window.localStorage.getItem("devicetoken");
var usr = new Usr({ username: rid });
usr.set({sendnotification: true });
usr.save({
  success: function(model, result, options) { console.log('saved'); },
  error: function(model, result, options) {console.debug('failed:'+result.error);}
});

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找到答案后，您需要直接使用用户对象。没有必要扩展模型

    var user = new StackMob.User({ username: rid, sendnotification: true});
    user.save({
        success: function(model, result, options) { console.log('saved'); },
        error: function(model, result, options) {console.debug('failed:'+result.error);}
    });