Load JSON data into Angular 2 Component

Question

I am trying to load JSON hada into an Angular 2 Component, and I think I have found the way.

datoer.service.ts:

import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { Observable } from 'rxjs/Observable';

@Injectable()
export class DatoService { 

    dato: Array<any>;

    constructor(private http: Http) {}

        getDato() {
            return this.http.request('./datoer.json')
                 .map(res => res.json());
        }   
}

kalender.component.ts:

import { Component } from '@angular/core';
import { ValgteSkolerService } from '../valgteSkoler.service';
import { DatoService } from './datoer.service';

@Component({
    selector: 'kalender',
    providers: [DatoService],
    templateUrl: 'app/kalendervisning/html/kalender.html'
})
export class KalenderComponent {

    private valgteSkoleRuter: Array<any>= [];
    //private datoer: Array<any> = [];

    constructor(private valgteSkolerService: ValgteSkolerService, private DatoService: DatoService) {
        this.datoer = this.DatoService.getDato();
    }

    ngOnInit() {
      this.valgteSkolerService.hentLagretData();
      this.valgteSkoleRuter = this.valgteSkolerService.delteValgteSkoleRuter;
    }

My template is like:

<p *ngFor="let dato of datoer"> {{dato}}  </p>

My problem is the this.datoer above in the component. It says it does not exist on type KalenderComponent. I have tried declaring it like this in the component:

private datoer: Array<any> = [];

But then it says that "Type 'Observable' is not assignable to type 'any[]'. Property 'length' is missing in type 'Observable'.

Any ideas how to solve this?

lenilsondc · Accepted Answer · 2016-10-25 14:29:30Z

2

The http service, according to Angular2 Http class docs, returns an observable not an array with results, that's because it's made asynchronously. Therefore you must subscribe to the observable so you can feed your array when it gets notified (this happens when http request is complete).

For example:

public datoer: any[] = [];    
constructor(
    private valgteSkolerService: ValgteSkolerService,
    private DatoService: DatoService) {

    this.DatoService
        .getDato()
        .subscribe(datoer => { this.datoer = datoer; });    
}

edited Oct 25, 2016 at 14:29

answered Oct 25, 2016 at 14:20

lenilsondc

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12 Comments

MariusJ Over a year ago

"GET localhost:3000/datoer.json 404 (Not Found)". What can be wrong?

lenilsondc Over a year ago

@MariusJ Your url can be wrong or mistyped or even the file doesn't exists. But that have nothing to do with the observable but with the HTTP request.

lenilsondc Over a year ago

@MariusJ, have you figured this out?

MariusJ Over a year ago

I only have 1 problem; cell.id = this.datoer[this.j].dato; doesn't work. Cannot read property dato of undefined...

lenilsondc Over a year ago

@MariusJ Where are you calling this from? on the component class? Could you add this piece of code on your question?

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