如何从 Angular 中的 JSON 字符串中获取数据进出 typescript 接口

Question

I am trying to set a user object from a JSON string gotten from localStorage.

let jsonObj: any = 
JSON.parse(localStorage.getItem('userId'));
this.user = (jsonObj as User)

This call:

console.log(JSON.stringify(this.user));

Produces the expected result:

 [{"firstName":"Thom","lastName":"Thumb","username":"Tiny",
    "password":"123456","streetAddress":"587 Elm St.",
 "city":"Cleveland","state":"Ohio","country":"USA",
"postalCode":"45678","email":"thom.thumb@gmail.com","id":5}]

However, when I try to extract a specific value:

        console.log(this.user.username);

It returns undefined. I need to extract the value to assign it to another object.

This is what 'user' looks like:

export interface User {
id: number;
username: string;
password: string;
firstName: string;
lastName: string;
streetAddress: string;
city: string;
state: string;
country: string;
postalCode: string;
email: string;
token: string;
}

Answer 1

You are getting an array of user. Use:-

console.log(this.user[0].username);

As you can see in your given output, it starts with [ and ends with ],this means it is an array.

[{"firstName":"Thom","lastName":"Thumb","username":"Tiny", "password":"123456","streetAddress":"587 Elm St.", "city":"Cleveland","state":"Ohio","country":"USA", "postalCode":"45678","email":"thom.thumb@gmail.com","id":5}]