Executing a Parent Function from a Child Component in Angular 11

Question

Executing a Parent Function from a Child Component in Angular 11

I have successfully passed values between Angular components using Input/Output several times before, but I am currently facing a unique situation for which I cannot find a solution:

There are two components involved:

home.component (parent component)

The parent component contains another navigation component that displays tabs from an external library. This navigation component is responsible for loading the child component: "task.component".

html file:

<div>
<app-tabs [tabs]="tabs" [activeTab]="activeTab" (id)="onId($event)"></app-tabs>
</div>

ts file:

onId($event) {
    // $event would contain the id obtained in the child component
}

tasks.component (child component)

The child component has a button click event that needs to communicate with the parent component:

html file:

<button type="button" (click)="play('task/play', 30)">Play</button>

ts file:

@Output() id= new EventEmitter<number>();
play(url: string, id: number) {
this.tasksService.playTask(url).subscribe(
  response => {
    // Here, I need to access a method in the parent component.
    // this.id.emit(id);
  },
  err => {
  }
);
}

In previous cases, passing parameters between child and parent components was straightforward because I used custom components. However, when working with an intermediate tab component, this becomes a challenge. It seems that directly passing the "Output" to the "app-tabs" component is not feasible.

Any suggestions on how to overcome this issue?

angular typescript

Answer 1

Answer №1

It appears that a child component (or grandchild component) is nested within a child route.

To address this issue, one approach could be to utilize a shared service for communication between the child component and its parent (or any other component in the application).

To achieve this, we would require an injectable service (or integrate it into an existing service):

In notification.service.ts:

@Injectable()
export class NotificationService {
  _taskPlayed$ = new Subject<number>();
  
  get taskPlayed$() {
    return this._taskPlayed$.asObservable();
  }
  
  taskPlayed(id: number) {
    this._taskPlayed$.next(id);
  }
}

Ensure to add this service to the module providers.

Subsequently, the service can be injected into the child (or any desired) component, allowing us to invoke the taskPlayed method to trigger a new value/event in the observable.

Thus, in child.component.ts:

export class ChildComponent {
  constructor(private notificationService: NotificationService) {}
  
  playTask() {
    this.notificationService.taskPlayed(1);
  }
}

Similarly, we inject the service into the parent (or any other relevant component), subscribing to the taskPlayed$ observable from the service (remembering to unsubscribe upon component destruction).

Hence, in parent.component.ts:

export class ParentComponent implements OnInit, OnDestroy {
  subscription!: Subscription;
  
  constructor(private notificationService: NotificationService) {}
  
  ngOnInit(): void {
    this.subscription = this.notificationService.taskPlayed$.subscribe((id) => {
      // perform actions with id...
      ....
    });
  }
  
  ngOnDestroy(): void {
    this.subscription?.unsubscribe();
  }
}

In the provided example, only the id value is transmitted via the Observable, but more complex objects can also be passed.

export class NotificationService {
  _taskPlayed$ = new Subject<{ id: number, title: string }>();
  
  get taskPlayed$() {
    return this._taskPlayed$.asObservable();
  }
  
  taskPlayed(task: {id: number, title: string}) {
    this._taskPlayed$.next(task);
  }
}

Answer 2

It appears that a child component (or grandchild component) is nested within a child route.

To address this issue, one approach could be to utilize a shared service for communication between the child component and its parent (or any other component in the application).

To achieve this, we would require an injectable service (or integrate it into an existing service):

In notification.service.ts:

@Injectable()
export class NotificationService {
  _taskPlayed$ = new Subject<number>();
  
  get taskPlayed$() {
    return this._taskPlayed$.asObservable();
  }
  
  taskPlayed(id: number) {
    this._taskPlayed$.next(id);
  }
}

Ensure to add this service to the module providers.

Subsequently, the service can be injected into the child (or any desired) component, allowing us to invoke the taskPlayed method to trigger a new value/event in the observable.

Thus, in child.component.ts:

export class ChildComponent {
  constructor(private notificationService: NotificationService) {}
  
  playTask() {
    this.notificationService.taskPlayed(1);
  }
}

Similarly, we inject the service into the parent (or any other relevant component), subscribing to the taskPlayed$ observable from the service (remembering to unsubscribe upon component destruction).

Hence, in parent.component.ts:

export class ParentComponent implements OnInit, OnDestroy {
  subscription!: Subscription;
  
  constructor(private notificationService: NotificationService) {}
  
  ngOnInit(): void {
    this.subscription = this.notificationService.taskPlayed$.subscribe((id) => {
      // perform actions with id...
      ....
    });
  }
  
  ngOnDestroy(): void {
    this.subscription?.unsubscribe();
  }
}

In the provided example, only the id value is transmitted via the Observable, but more complex objects can also be passed.

export class NotificationService {
  _taskPlayed$ = new Subject<{ id: number, title: string }>();
  
  get taskPlayed$() {
    return this._taskPlayed$.asObservable();
  }
  
  taskPlayed(task: {id: number, title: string}) {
    this._taskPlayed$.next(task);
  }
}

Executing a Parent Function from a Child Component in Angular 11

Answer №1

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