mergeAll not working the same as a lettable operator (rxjs 5.5+)?

Question

Before lettable operators, the code looked like this:

get someData$(): Observable<Data> {
  return this.dataService.higherOrderDataStream
    .mergeAll()
    .map(...);
}

Refactoring to use pipe, I get a type error essentially saying Observable<Observable<Data>> is not assignable to type Observable<Data>:

get someData$(): Observable<Data> {
  return this.dataService.higherOrderDataStream
    .pipe(
      mergeAll(),
      map(...)
    );
}

But the following works just fine (I assume one shouldn't mix lettable and chained operators):

get someData$(): Observable<Data> {
  return this.dataService.higherOrderDataStream
    .mergeAll()
    .pipe(
      map(...)
    );
}

Is there a different mergeAll I should be using? I'm using the one from rxjs/operators where I was using rxjs/add/operator/mergeAll previously. I thought these two implementations would be equivalent.

Is this a bug or am I using the new mergeAll incorrectly?

martin · Accepted Answer · 2018-03-15T15:38:04.563

2

This is a known bug in RxJS 5.5 with mergeAll and concatAll. It'll be fixed in RxJS 6.

For more details see: https://github.com/ReactiveX/rxjs/issues/2759

Fix was merged few days ago: https://github.com/ReactiveX/rxjs/pull/3321

For now it's better to use mergeMap(o => o) or concatMap(o => o) instead.

edited Mar 15 '18 at 15:38

answered Feb 20 '18 at 15:25

martin

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Whew. Thanks for the info and links (upvoted). Going to try this in my code now and will accept if it works. – vince Feb 20 '18 at 15:35
Works like a charm. – vince Feb 20 '18 at 15:37

mergeAll not working the same as a lettable operator (rxjs 5.5+)?

1 Answers1