为RxJS的subscription（）中的组件变量分配一个值

Question

I'm trying to subscribe to an observable source in order to bind the source's value to a component variable ( event: Event ).

In spite of the fact that the observer function passed to the subscribe() function executes correctly, and the observable arrives at expected, the component variable event: Event is always undefined.

Why is that happening and how can I solve this problem?

@Component({
    selector: 'event-detail',
    template: `
        <div *ngIf="event"> <-- this will never evaluate to 'true'
            ...
        </div>
    `,
})
export class EventCenterDetailComponent implements OnInit {
    event: Event;
    subscription: Subscription;

    constructor(
        private eventBus: EventBus
    ) {}

    ngOnInit() {
        this.subscription = this.eventBus.event$.subscribe((event: Event) => {
            this.event = event; <-- this assignment seems to have no effect on the component variable
        });
        console.log(this.event); <-- this is 'undefined'
    }

Answer 1

Only explanation here is that event in the subscribe is not coming down properly. You will see that event is undefined if you try to print it in the subscribe block

...subscribe((event: Event) => {
   console.log(event); // this will print undefined most likely
});

Then you have to fix your EventBus service