Question

我使用http.get调用从后端服务器获取JSON对象，并试图从该对象检索数据，但是我收到“ TypeError：obj.attr未定义”。（注意：我已经验证了JSON对象的发送/接收没有任何问题，并且格式符合预期）。我应该如何引用对象中的特定字段以避免上面的错误？

后端对象数据模型（来自Express users_controller.js）

exports.user_create_get = function(req, res, next) {
    var authObj = new Auth({
        dateEffective: {value: moment(Date.now()), attr: {hidden: true}},
        username: {value: '', attr: {hidden: false, label: "Username: "}},
        password: {value: '', attr: {hidden: false, label: "Password: "}},
        mainEmail: {value: '', attr: {hidden: false, label: "Email: "}}
    });
    var user = new UserObj({
        authData: [authObj] })
      res.json(user);
};

使用前端Angular代码消耗数据（app.component.ts）：

  ngOnInit() {

    this.member.getMemberForm().subscribe((data)=>{
      this.keys = Object.keys(data["authData"][0]);
      this.keys.forEach(key => {
        let obj = data["authData"][0][key];
        console.log("Key: " + key + "; " +   
          obj["attr"]["label"]);           // <--- ERROR OCCURS HERE
      });
      if (this.data) this.got_data = true; 
    });

这是字符串化的JSON对象：

{ "_id": "5ced5e4e7da71157709ef1a6", 
    "authData": [ { "_id": "5ced5e4e7da71157709ef1a5", 
        "dateEffective": { "value": 1559060046775, 
            "attr": { "hidden": true, "label": "Date: " } }, 
        "username": { "value": "", 
            "attr": { "hidden": false, "label": "Username: " } }, 
        "password": { "value": "", 
            "attr": { "hidden": false, "label": "Password: " } }, 
        "mainEmail": { "value": "", 
            "attr": { "hidden": false, "label": "Email: " } } } ] 
}

如何解决：TypeError：项目“未定义”？

0 个答案: