Ndtyjky

Response on my main subscription call returns an array of some values. These values are passed as arguments to array of my child subscriptions. In these subscriptions I want to assign values to dataArr - when subscription receives 'Not found' error, then I want to assign custom value. When all of the subscriptions are called then I want to execute final code after last subscription call.

Problem is I can't achieve it with forkJoin, because according to RxJS documentation "If an inner observable does not complete forkJoin will never emit a value!". I've tried merge and concat operators too. Any ideas?

this.service.get().subscribe(response => {

  this.observables = ;

  this.dataArr = ;



  response.items.forEach(item => {

    this.observables.push(this.otherService.get(item.data))

    // I want this subscription to make this action

    // this.otherService.get(item.data).subscribe(

    //   response => {

    //     this.dataArr.push({

    //       title: response.title,

    //     });

    //   },

    //   error => {

    //     this.dataArr.push({

    //       title: 'Not found!',

    //     });

    //   }

    // )

  });



  Observable.forkJoin(this.observables).subscribe(

    res => {

      console.log(res)

    }, err => {

      console.log(err);

    }, () => {

      console.log('Completed!');

      // execute other code on completion

    }

  );

});

You can use forkJoin!

https://www.learnrxjs.io/operators/combination/forkjoin.html

Be aware that if any of the inner observables supplied to forkJoin error you will lose the value of any other observables that would or have already completed if you do not catch the error correctly on the inner observable. If you are only concerned with all inner observables completing successfully you can catch the error on the outside.

So, just make sure that when an observable throws an error, it will still return something:

    forkJoin(

        this.service.observableA.pipe(

            map(data => {

                return { result: 'succes', data: data };

            }),

            catchError(err => {

                console.log(err);

                return of({ result: 'failed', data: null });

            })

        ),

        this.service.observableB.pipe(

            map(data => {

                return { result: 'succes', data: data };

            }),

            catchError(err => {

                console.log(err);

                return of({ result: 'failed', data: null });

            })

        )

    ).subscribe(

        // This will be triggered even if one of the observables fail

    );

Of course, in the subscribe method, you will need to inspect the list, and check if the 'result' properties is 'succes' or 'failed' for each returned response.