RxJS complete Observable from within switchmap

Question

I have an HTTP call that does a switchMap to a Promise<boolean>. If that promise returns false, I need it to close the observable. Here is some example code

private method2() : Observable<MyModel> {
      return this.service.httpCall().pipe(
            switchMap(
                async (model: MyModel) =>
                {
                    const navResult = await this.router.navigate(...);
                    // Navigation can still fail. This Observable hence should only complete when navigation completes
                    if (navResult)
                    {
                        return model;
                    }
                    // If navResult fails, I need this observable to close.
                    // Do I just not return anything? Leaving the subscriber waiting for ever? Or do I need to explicitly close it? If so, how?
                    // return EMPTY does not work because of the explicitly declared return type.
                }));


private method1()  {
  this.method2().pipe(tap((result) => {
      // Some logic which should only be called when the `navResult` inside the second method is `true`
    }), 
    catchError(error => {
      // Some logic which should only be called when `method2` throws an error
    });
}

But the problem now is that method2 is not closing the observable when navResult is false.

Answer 1

You have 2 choices:

• Either your inner observable throws on fail and you catch that in the subscribe
• You filter after the switchMap to prevent the observable from emitting a value. (and it will complete because of the http request usually completes the observable).