Can I subscribe inside the combineLatest by the return result?

February 26, 2022

I want to use combineLatest to get a bunch of result. Then one of result is passed as input parameter to do another subscribe call.

combineLatest([first, second, third, four, five]).pipe(take(1)).
   subscribe(([a, b, c, d, e]) => {
        this.showData1(a);
        this.showData2(b);
        this.showData3(c);
        this.showData4(d);
        if(e > 8) {
           this.myService.updateStatus(e).subscribe(
              result => this.setupStatus(result)
           );
       }
   });

The logic is from the 5 results, 4 of them are used for rendering screen. The last one I use it to do a subscribe, its returning result will used some where.

But I feel that it is not right because sometimes it seems this.setupStatus(result) is not running inside the combineLatest. Memory leak?

>Solution :

hard to diagnose why it wouldn’t be running without knowing more about the observables. but I’d do it something like this to avoid nested subscribes and make this a little easier to diagnose / manage:

combineLatest([first, second, third, four, five]).pipe(
   take(1),
   switchMap(([a, b, c, d, e]) => {
        this.showData1(a);
        this.showData2(b);
        this.showData3(c);
        this.showData4(d);
        return this.myService.updateStatus(e);
   })
).subscribe(result => this.setupStatus(result));

possibly structuring a little differently depending on when exactly I want things to happen.