ngrx效应--结合两个API

Question

我有下面的效果，使用以下方法更新对象的一部分 update api，然后我就可以通过 findById api，所以我用了 forkJoin 将这两个api结合起来，但我想让这个 findById 的api在1秒后被执行。update api，所以我用了 delay(1000)但它不工作

@Effect()
updateGeographicScope$ = this.actions$.pipe(
    ofType<conventionsActions.PatchGeographicScope>(conventionsActions.ConventionActionTypes.PATCH_GEOGRAPHIC_SCOPE),
    map(action => action.payload),
    exhaustMap(geographicScope => forkJoin(this.apiConvention.update(geographicScope),
        this.apiConvention.findById (geographicScope.externalId).pipe(delay(1000))).pipe(
            map(([first, convention]) => new conventionsActions.PatchSuccess({
                id: convention.externalId,
                changes: convention
            })),
            catchError(err => {
                console.error(err.message);
                return of(new conventionsActions.Failure({ concern: 'PATCH', error: err }));
            })
        ))
);

Answer 1

你需要使用一个 concat 和 timer 为，。随着 concat 在开始下一个流之前，它先完成第一个流。所以它先进行update，然后等待1秒，再进行findById。

@Effect()
updateGeographicScope$ = this.actions$.pipe(
    ofType<conventionsActions.PatchGeographicScope>(conventionsActions.ConventionActionTypes.PATCH_GEOGRAPHIC_SCOPE),
    map(action => action.payload),
    mergeMap(geographicScope => concat(
      this.apiConvention.update(geographicScope).pipe(switchMapTo(EMPTY)), // makes a request
      timer(1000).pipe(switchMapTo(EMPTY)), // waits 1 sec
      this.apiConvention.findById(geographicScope.externalId), // makes a request
    )),
    map(convention => new conventionsActions.PatchSuccess({
      id: convention.externalId,
      changes: convention
    })),
    catchError(err => {
      console.error(err.message);
      return of(new conventionsActions.Failure({ concern: 'PATCH', error: err }));
    }),
    repeat(), // make active after a failure
  )),
);