Angular service promise first is undefined

Question

Today I started with Angular 2 and already came across an error I can't solve.

I have an 'opdracht' service which is loading data out of a mock file. The opdracht component is 4 times in the home component. The first is undefined and the last 3 are showing.

I think there is something wrong with the promise. But I can't figure out what. The code and the console error is down here.

What am I doing wrong?

Thanks,

Maarten

Console error

main.bundle.js:41251EXCEPTION: Uncaught (in promise): Error: Error in ./OpdrachtComponent class OpdrachtComponent - inline template:0:3 caused by: Cannot read property 'name' of undefined

opdracht.ts

export interface Opdracht {
  id: number;
  name: string;
}

opdrachten.mock.ts

import { Opdracht } from "./opdracht";

export const OPDRACHTEN: Opdracht[] = [
  {
    id: 1,
    name: "Apple iDrive"
  },
  {
    id: 2,
    name: "Lunchroom Bakker"
  },
  {
    id: 3,
    name: "Augmented Albert"
  },
  {
    id: 4,
    name: "Pecha Kucha"
 }
];

opdrachten.service.ts

import {Injectable} from "@angular/core";
import {Opdracht} from "./opdracht";
import {OPDRACHTEN} from "./opdrachten.mock";

@Injectable()
export class OpdrachtenService {

  getOpdracht(id: any): Promise<Opdracht> {
    return Promise.resolve(OPDRACHTEN[id]);
  }
}

opdracht.component.ts

import {Component, OnInit, Input} from "@angular/core";
import {OpdrachtenService} from "../services/opdrachten/opdrachten.service";
import {Opdracht} from "../services/opdrachten/opdracht";

@Component({
  selector: 'app-opdracht',
  templateUrl: './opdracht.component.html',
  styleUrls: ['./opdracht.component.scss'],
  providers: [OpdrachtenService]
})
export class OpdrachtComponent implements OnInit {

  @Input() private id: any;

  protected opdracht: Opdracht;

  constructor(private opdrachtenService: OpdrachtenService) { }

  getOpdracht(): void {
    this.opdrachtenService.getOpdracht(this.id)
      .then((opdracht: Opdracht) => {
        this.opdracht = opdracht
      })
    ;
  }

  ngOnInit() {
    this.getOpdracht();
  }
}

opdracht.component.html

<p>{{ opdracht.name }}</p>

home.component.html

<app-header></app-header>
<app-foto></app-foto>
<app-ik></app-ik>
<app-opdracht [id]="0"></app-opdracht>
<app-opdracht [id]="1"></app-opdracht>
<app-opdracht [id]="2"></app-opdracht>
<app-opdracht [id]="3"></app-opdracht>
<app-footer></app-footer>

You are calling opdracht with id 0 but you don't have it in your mock file. — Sefa, Oct 08 '16 at 16:22
The input name 'id' is a bit misleading. I'm using it as an index. — maartenpaauw, Oct 08 '16 at 16:25

score 2 · Accepted Answer · answered Oct 08 '16 at 16:28

2

Use the safe-navigation operator to avoid errors when Angular evaluates the binding but async values have not yet arrived:

<p>{{ opdracht?.name }}</p>

answered Oct 08 '16 at 16:28

Günter Zöchbauer

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Thank you. This solved the problem! – maartenpaauw Oct 08 '16 at 16:32
Glad to hear :) – Günter Zöchbauer Oct 08 '16 at 16:33

Angular service promise first is undefined

1 Answers1