Making two http requests sequentially in angular, rxjs

Question

Currently I have the following request:

      return this.registrationService.registratePerson(data).pipe(
        switchMap(
          res => {
            return this.registrationService.sendPassportScan(this.form.value.passportScanCopyFile, res.AisUserIsn);
          }
        )
      );

The second request makes use of the result obtained in the first one, that's something that I need but the problem with it is that now it returns what comes from the second request (the inner one). Is it possible somehow with the help of rxjs operators to make it return an observable containing fields from the inner request as well as those from the outer one?

In the application the 5th version of rxjs is used.

mbojko · Accepted Answer · 2019-10-25 07:19:01Z

1

Sure. Something like this:

return this.registrationService.registratePerson(data).pipe(
    switchMap(
        res => forkJoin(
            of(res), 
            this.registrationService.sendPassportScan(/* relevant args */),
        )))

(The resulting stream will contain a 2 element array).

answered Oct 25, 2019 at 7:19

mbojko

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2 Comments

igor Over a year ago

Yeah that's exactly what I was looking for! And if, say, I want to flatten that array, I can do this in map that I will have to add right after switchMap, right?

mbojko Over a year ago

Yes, map will do that.

Duy Đoàn · Accepted Answer · 2019-10-25 07:43:45Z

0

concatMap may help you in this case

https://www.learnrxjs.io/operators/transformation/concatmap.html

Example https://angular-academy.com/rxjs-switchmap-concatmap-mergemap-exhaustmap/#concatmap

answered Oct 25, 2019 at 7:43

Duy Đoàn

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