What is the best way to eliminate chaining within this code through the use of behavior subjects?

Question

What is the best way to eliminate chaining within this code through the use of behavior subjects?

Is there a way to optimize the code below by utilizing behaviorsubjects rather than chaining, ensuring that any failures in function calls do not impact the UI's access to data from other functions?

this.service.getElementById(this.elementId)
  .pipe(mergeMap((element) =>
    zip(
      of(element),
      this.service.getReport(this.elementId, this.year, this.month)
    ))
  )
  .pipe(mergeMap(([element, report]) =>
    zip(
      of(element),
      of(report),
      this.service.getChanges(this.elementId, report.lineId)
    ))
  )
  .subscribe(([element, report, changes]) => {
    this.paymentProvider = provider;
    this.mapToSummary(report);
    this.lineId = report.lineId;
    this.changes = changes;
  })

javascript angular typescript asynchronous rxjs

Answer 1

Answer №1

Follow these steps to achieve the desired outcome:

this.service
  .getElementById(this.elementId)
  .pipe(
    mergeMap((element) => {
      const report$ = this.service
        .getReport(this.elementId, this.year, this.month)
        .pipe(
          catchError(() => of(null)),
          shareReplay({ bufferSize: 1, refCount: true })
        );

      const changes$ = report$.pipe(
        mergeMap((report) =>
          !report
            ? of(null)
            : this.service
                .getChanges(this.elementId, report.lineId)
                .pipe(catchError(() => of(null)))
        )
      );

      return forkJoin({
        element: of(element),
        report: report$,
        changes: changes$,
      });
    })
  )
  .subscribe(({ element, report, changes }) => {
    // implement your logic here
    // keep in mind that report and changes may be null now
  });

By following this approach, you can ensure that any errors do not affect the entire observable stream.

Answer 2

Follow these steps to achieve the desired outcome:

this.service
  .getElementById(this.elementId)
  .pipe(
    mergeMap((element) => {
      const report$ = this.service
        .getReport(this.elementId, this.year, this.month)
        .pipe(
          catchError(() => of(null)),
          shareReplay({ bufferSize: 1, refCount: true })
        );

      const changes$ = report$.pipe(
        mergeMap((report) =>
          !report
            ? of(null)
            : this.service
                .getChanges(this.elementId, report.lineId)
                .pipe(catchError(() => of(null)))
        )
      );

      return forkJoin({
        element: of(element),
        report: report$,
        changes: changes$,
      });
    })
  )
  .subscribe(({ element, report, changes }) => {
    // implement your logic here
    // keep in mind that report and changes may be null now
  });

By following this approach, you can ensure that any errors do not affect the entire observable stream.

What is the best way to eliminate chaining within this code through the use of behavior subjects?

Answer №1

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