Angular2 - Waiting for service variable to be initialized

Question

Application

• MapViewComponent
• SearchComponent (requires an object of the MapViewComponent)
• MapService

So far, I placed the Se

Answer 1

You should use a Subject (either BehaviorSubject or ReplaySubject). The Subject will act as both a producer and consumer. The consumer of it can subscribe to it, just like an observable. And the producer can use it to emit messages to consumers. For example

import { ReplaySubject } from 'rxjs/ReplaySubject'

@Injectable()
export class MapService {

  private _currentMapView = new ReplaySubject(1);

  setCurrentView(mv: MapView){
    this._currentView.next(mv);
  }

  get currentMapView$() {
    return this._currentMapView.asObservable();
  }
}

The subscriber just needs to suscribe

import { Subscription } from 'rxjs/Subscription';

export class SearchComponent {
  sub: Subscription;
  view: MapView;

  constructor(private elRef:ElementRef, private mapService: MapService ) {
  }

  ngOnInit() {
    this.sub = this.mapService.currentMapView$.subscribe(view => {
      this.view = view;
    })
  }

  ngOnDestroy() {
    if (this.sub) {
      this.sub.unsubscribe();
    }
  }
}

The MapViewComponent just needs to call the setCurrentView, and it will be handled by the subscribers automatically when it's sent

See Also:

• This post for a brief description about difference between Subject/BehaviorSubject/ReplaySubject