Angular 2 Typescript parse json to object

Question

I am newbie to Angular2 and Typescript. I am learning nowadays. I try to get data from a REST service then I want to make a list and insert this data which comes from the service. So my API link is http://jsonplaceholder.typicode.com/users/1

here is my HttpTestService.ts code;

import {Component} from '@angular/core';
import {Http} from '@angular/http';
import {Headers} from '@angular/http';
import {Observable} from 'rxjs/Observable';
import {Injectable} from '@angular/core';

import 'rxjs/add/operator/map';

@Injectable()
export class HTTPTestService{
  constructor(private _http:Http){}
    getUser(){
      return this._http.get("http://jsonplaceholder.typicode.com/users/1")
      .map(res=>res.json());
    };
}}

Here is my HttpTestComponent.ts;

import { Component } from '@angular/core';
import {HTTPTestService} from './http-test.service';
import { User } from './user';

@Component({
  selector:'http-test',
  template:`
    <button (click)="onGet()">Get Data</button><br/>
    <div>Output:{{getData}}</div><br/>
    <button (click) = "onPost()">Post Data</button><br/>
    <div>Output:{{postData}}</div><br/>
    <button (click) = "onPromiseGet()">Get Data(w Promise)</button><br/>
    <div>Output:{{getPromiseData}}</div><br/>
  `,
  providers:[HTTPTestService]
})

export class HTTPTestComponent{
  getData:string;
  getPromiseData:string;
  postData:string;


  constructor(private _httpService:HTTPTestService){}

  onGet(){
    console.log('Getting user now.');
    this._httpService.getUser().subscribe(        
      data =>this.getData = JSON.stringify(data),
      error=>alert(error),
      ()=>console.log('Finished Get')      
    );         
  }}

And here is my User.ts

 export class User{
  constructor(public id: number,public name:string) { }
 }

How do I fill my User class and then how do I add a generic list to my User class.

Best regards

Do you want to create a new object with id and name only or use whole structure received from server? — Patryk Brejdak
– Patryk Brejdak, Commented Nov 16, 2017 at 11:44
server send many paramaters but i just only fill id and name to my structure. is it possible or i should write all parameter which server send ? — user1436795
– user1436795, Commented Nov 16, 2017 at 11:52
No, you don't have to, and tell me more about generic list in User class, what do you mean by this? — Patryk Brejdak
– Patryk Brejdak, Commented Nov 16, 2017 at 11:56
like csharp; var myUserlist = new List<User>(); myUserList.add(new User{id = 1,name = "aaa"}) this new User fill from by rest — user1436795
– user1436795, Commented Nov 16, 2017 at 11:56

Patryk Brejdak · Accepted Answer · 2017-11-16 12:19:37Z

3

As far as I understand your question, just create a new Object of User type and pass desired data, in your case it is id and name.

private userList: Array<User> = new Array<User>();

onGet(){
    console.log('Getting user now.');
    this._httpService.getUser().subscribe(        
      data => this.parseUser(data),
      error=>alert(error),
      ()=>console.log('Finished Get')      
    );         
  }

parseUser(data) {
   let user = new User(data.id, data.name);
   this.userList.push(user);
}

To create list of users just make an array of User like that private Users: Array<User> = new Array<User>(); remember to import User.

EDIT. For test purpose change this

@Component({
  selector:'http-test',
  template:`
    <button (click)="onGet()">Get Data</button><br/>
    <div>Output:{{getData}}</div><br/>
    <button (click) = "onPost()">Post Data</button><br/>
    <div>Output:{{postData}}</div><br/>
    <button (click) = "onPromiseGet()">Get Data(w Promise)</button><br/>
    <div>Output:{{getPromiseData}}</div><br/>

    <div *ngFor="let user of userList">
       <p>Id: {{user.id}}</p>
       <p>Name: {{user.name}}>/p>
       <br />
    </div>
  `,
  providers:[HTTPTestService]
})

When response come angular will print data :)

edited Nov 16, 2017 at 12:19

answered Nov 16, 2017 at 12:00

Patryk Brejdak

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11 Comments

user1436795 Over a year ago

data => parseUser(data), should be data => this.parseUser(data) ?

user1436795 Over a year ago

thanks for your answer but when turn list it comes nothing; console.log('Start List') for (var v in this.userList) { console.log("My First Element: "+ this.userList[v].id); } console.log('End List') userList.Length = 0. I think it didnt parse or it didnt push correctly. Because i get data before parsing. where am i wrong ?

Patryk Brejdak Over a year ago

That's strange, maybe you have a typo, check you console for errors and I would like suggest you to use for .. of .. loop for example it would be for(let user of this.userList) { console.log("user id: " + user.id) }

user1436795 Over a year ago

Userlist.length = 0; so it didnt write anything ? are you sure that this parse method working fine ? Because you dont use any Json.parse etc ?

Patryk Brejdak Over a year ago

Referring to your service

getUser(){       return this._http.get("http://jsonplaceholder.typicode.com/users/1")       .map(res=>res.json());     };

is parsing it to JSON :). remember that evaluating callback for subscribe is asynchronous so check the place where you are calling this or show me the code :).

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