Retry observable queue three times (from the index where it failed)-CodePudding

I got an array of observables. I want to subscribe to each observable source provided only one at a time and not to subscribe to the next until the previous one is finished. If any fails I'd like to retry from the observable that failed (for a couple more times). I don't find a good, smart way to do that.

I'm sure there is more than one way, but I'm not even close to being 'fluent' in rxjs so I'm a bit lost rn. The project I'm working on is using rxjs 6.4.

Cheers and ty!

CodePudding user response：

You can use retry(X) inside concatMap() but it really depends on what behavior exactly you want:

source$
  .pipe(
    concatMap(val => makeRequest(val).pipe(
      retry(3), // Will retry only this request 3 times.
    )),
  );

With concat:

concat(...sources.map(obs => obs.pipe(retry(3))))
  .subscribe(result => {});

CodePudding user response：

You can use the RxJS operators SwitchMap and retry. The SwitchMaps chain the observables so that each one waits for the last to emit something.

obs1.pipe(
  retry(2)
  switchMap(res1 => obs2.pipe(retry(2)))
  switchMap(res2 => obs3.pipe(retry(2)))
).subscribe(res3 => console.log(res3))

EDIT:

What to do if you don't know the amount of observables:

let arr = [obs1$, obs2$, obs3$]

of(arr).pipe(
  ...(arr.reduce((p, q) => [...p, switchMap(e), retry(2)]))
).subscribe(console.log)