在 Angular 服务中取消订阅 observable

Question

I want to unsubscribe an observable in an angular service once a certain state is present. The unsubscribe should be executed within the subscription. Unfortunately the code below does not work.

@Injectable()
export class CartManagementUsecase {
  private unsubscribe = new Subject();

  public streamSession(): void {
    this.adapter
        .streamSession()
        .pipe(takeUntil(this.unsubscribe))
        .subscribe((session) => {
          if(session.session_state === SessionState.CLOSED) {
            this.unsubscribe.unsubscribe();
          }
    });
  }
}

Answer 1

You need to call complete on your subject for takeUntil to unsubscribe to the observable.

@Injectable()
export class CartManagementUsecase {
  private unsubscribe = new Subject();

  public streamSession(): void {
    this.adapter
        .streamSession()
        .pipe(takeUntil(this.unsubscribe))
        .subscribe((session) => {
          if(session.session_state === SessionState.CLOSED) {
            this.unsubscribe.complete();
          }
    });
  }
}

Answer 2

I would recommend you to take events untill closed is come. no subject would be required

public streamSession(): void {
    this.adapter
        .streamSession()
        .pipe(takeWhile(session => session.session_state != SessionState.CLOSED))
        .subscribe((session) => {
          // do something that is required
        });
  }