在Angular 2中等待来自Store的嵌套观察值

import { Component, OnInit } from '@angular/core';
import { Store } from '@ngrx/store';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@Component({
  selector: 'app-example',
  template: `
    <div *ngIf="nestedValue$ | async as nestedValue">
      Nested Value: {{ nestedValue }}
    </div>
  `,
})
export class ExampleComponent implements OnInit {
  nestedValue$: Observable<any>;

  constructor(private store: Store<any>) {}

  ngOnInit() {
    this.nestedValue$ = this.store.select('parentKey').pipe(
      map((state) => state.childKey)
    );
  }
}