Rxjs - 在 concatMap() 中订阅不会触发点击

Question

我有一个映射可观察对象的主题，我订阅了 concatMap 中的可观察对象，但它不会从订阅中触发 tap()。

this.streamA$ = this.streamService.getStream(1)
      .pipe(
        tap(data => console.log('stream data:', data))
      );

主题

this.images$ = this.queue.pipe(concatMap((event: Observable<string>) => {
      // when an event arrives here it is still wrapped in observable

      // subscribe isn't triggering tap()
      event.subscribe(data => {
        //console.log('inner observable subscription:', data);
      });

      // observable goes to the image$ observable, it is unwrapped by: image$ | async in template
      return event;
    }));

服务功能

  getStream(time: number): Observable<string> {

    let timer$ = timer(2000);
    console.log('get stream');

    const observable = new Observable<string>(observer => {

      timer$.pipe(
        map(() => {
          observer.next('http response 1');
          observer.complete();
        })
      ).subscribe();

    });
    return observable;
  }

---

更新：

event.subscribe(data => {
         //console.log('inner observable subscription:', data);
      });

订阅中不包含console.log，这是输出：

stream data: http response 1

使用console.log，同时打印这3行：

stream data: http response 1
inner observable subscription: http response 1
stream data: http response 1

Answer 1

当你在 concatMap 中有一个 Observable 时，你不需要订阅。你能尝试一下这些方法吗？

this.images$ = this.queue.pipe(
  concatMap(event => event), // I assume the event here is something like this.streamA$
  tap(data => // do stuff with data)
);