How can I continue to call API after get error when using rxjs concat?

Question

I am using concat to call multiple API sequentially, but when error, concat stop call api, so how to get error and continue to call next API, here is my code:

getData() {
    concat(...this.data.map(asset =>
      this.assetService.requestData({ assetId: asset._id })
    ))
      .pipe(catchError(error => {
        console.log(error);
        // return of(null);
        this.error = error;
        return throwError(error);
      }))
      .subscribe();

  }

you can try to add .retry(N) before pipe() function is called — akkonrad
– akkonrad, Commented Dec 9, 2019 at 9:51
@akkonrad but I want after 5 times trying if it still get error, I can continue to get another api — hem6d
– hem6d, Commented Dec 9, 2019 at 9:54

s.alem · Accepted Answer · 2019-12-09 10:09:20Z

1

Error catching should happen individually for each observable. You can simply return an empty observable:

import { EMPTY } from 'rxjs';

concat(...this.data.map(asset =>
  this.assetService.requestData({assetId: asset._id})
    .pipe(catchError(error => {
      console.log(error);
      this.error = error;
      return EMPTY;
    }))
  ))
  .pipe(filter(data => !!data)) // add this line if you do not want to see nulls in result
  .subscribe();

Another option would be using onErrorResumeNext function:

import { onErrorResumeNext } from 'rxjs';

onErrorResumeNext(...this.data.map(asset => 
  this.assetService.requestData({assetId: asset._id})
)
.subscribe();

edited Dec 9, 2019 at 10:09

answered Dec 9, 2019 at 10:03

s.alem

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1 Comment

hem6d Over a year ago

the second way works with me but if how can get Error when using onErrorResumeNext? I tried to add pipe but it didn't work

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