Question

我正在尝试将JSON响应中的值设置为一些变量。但是未设置该值，并试图在Console.log（）中查看这些值时返回“ undefined”。

有人知道我在做什么错吗？

public data: any;
carbs: string;
fat:any;
protein:any;

constructor(public navCtrl: NavController,public userprovider: UserProvider) {

    //returns json array
    this.user = this.userprovider.getUser(userid);

    this.user.toPromise().then(res => {

        this.carbs = res[0].carbs;
        this.fat = res[0].fat;
        this.protein = res[0].protein;

    });

    console.log(this.carbs);
   //pass the data here
     this.data = {"Macros":[{"Macros":"Prot","time":this.protein,"color":"#3fa9f5","hover":"#57c0f5"},{"Macros":"Carb","time":this.carbs,"color":"rgb(236, 240, 241)","hover":"rgb(236, 240, 241)"},{"Macros":"Fat","time":this.fat,"color":"rgb(52, 73, 94)","hover":"rgb(52, 73, 94)"}]};


}

Answer 1

这是因为console.log(this.carbs);是在this.carbs = res[0].carbs;完成之前启动的。因此，不要在范围内调用函数，而应在范围内调用它。

从以下位置调用函数：

 this.user.toPromise().then(res => {

        this.carbs = res[0].carbs;
        this.fat = res[0].fat;
        this.protein = res[0].protein;
        this.yourFunction(res[0].protein, res[0].carbs, res[0].fat );
    });

。。

yourFunction(protein, carbs, fat){
 this.data = {"Macros":[{"Macros":"Prot","time":protein,"color":"#3fa9f5","hover":"#57c0f5"},{"Macros":"Carb","time":carbs,"color":"rgb(236, 240, 241)","hover":"rgb(236, 240, 241)"},{"Macros":"Fat","time":fat,"color":"rgb(52, 73, 94)","hover":"rgb(52, 73, 94)"}]};
}

使用IONIC框架的角度未定义变量

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