Pass Observable data from Parent Component to a Child Component created with componentFactoryResolver in Angular 2+

问题

I need help as I am a bit lost right now. So, I have a component that dynamically injets a child component into its template using componentFactoryResolver , here is my HTML

<div class="dialog">
    <div #container></div>
    <button (click)="move('back')">Back</button>
    <button (click)="move('forwards')">Forwards</button>
</div>

also in my component I have an observable that captures the click of the buttons like so, here is my (edited / reduced) code

// parent-component.ts

@ViewChild('container', {read: ViewContainerRef})
public dialogContainer: ViewContainerRef;

public navigationClick$: Observable<string> = new Subject<string>();

// click event on buttons
public move(direction): void {
    this.navigationClick$.next(direction);
}

// code to inject child dynamic component, please ignore the args / variables

const componentFactory = this.componentFactoryResolver.resolveComponentFactory(this.data.component);
this.componentRef = this.dialogContainer.createComponent(componentFactory);
this.embeddedcomponent = this.componentRef.instance as IWizardDialog;
this.embeddedcomponent.data = this.data.data;

Now I would like to pass the latest observable value from navigationClick$ to the child component I amend the code in my parent component thus...

const componentFactory = this.componentFactoryResolver.resolveComponentFactory(this.data.component);
this.componentRef = this.dialogContainer.createComponent(componentFactory);

// NEW CODE
// here I subscribe to the observable and try to pass the value to the child component
this.navigationClick$.subscribe((data: string) => {
  this.componentRef.instance.direction = data;
});

this.embeddedcomponent = this.componentRef.instance as IWizardDialog;
this.embeddedcomponent.data = this.data.data;

The subscribe is working in the parent as I would expect however I am unsure how I would capture / pass the subscribe data to the child component, for example can I just declare this as a Input()

// child-component.ts

@Input() public direction: string;

However this will just be undefined and isn't what I need. How do I pass the direction data from the subscribe to the child component or what code / feature do I need to receive the event / direction string? Any advice is appreciated.

If my wording is bad or confusing please say and I will rework the question.

回答1:

I would use a service. Not ViewChild. With a service the components would not need to know of each other

 @Injectable()
  export class YourService {
  move$: Observable<any>;
  private moveSubject: Subject<any> = new Subject();

  constructor() {
    this.move$ = this.moveSubject.asObservable();
  }

  public move(direction) {
     this.moveSubject.next(direction);
  }


}

Usage in parent

contructor(public yourService:YourService){
}

html in parent

<button (click)="yourService.move('back')">Back</button>

Usage in child

YourChild implements OnInit, OnDestroy {
    private subscriptions: Subscription = new Subscription();
    constructor(private yourService:YourService) {

    }
    ngOnInit(): void {
        this.subscriptions.add(this.yourService.move$.subscribe(direction => {
            //Do something
        }));        
    }
    ngOnDestroy(): void {
    this.subscriptions.unsubscribe();
}

}

来源：https://stackoverflow.com/questions/46487255/pass-observable-data-from-parent-component-to-a-child-component-created-with-com

标签

angular

angular2-observables