Chaining RXJS

chaining_rxjs.ts

const loginEpic = actions$ => 
actions$.ofType(ActionTypes.LOGIN_REQUESTED)
    .switchMap(
        (loginAction) => Observable.ajax(POSTOptions('/api/login', loginAction.credentials),
        (action, r) => ([r, action])
    )
    .switchMap(
       ([loginResponse, action]) => Observable.ajax(
            GETOptions('/api/provider', [loginResponse.response.userToken, action.serviceProviderId] )
       )
    )
    .map(providerResponse => loginResolvedAction(providerResponse.response));

// Real Example
@Effect()
LoadMorePotatoesList = this.actions
  .pipe(
    ofType(new PotatoesActions.LoadMorePotatoesAction().type),
    switchMap(() => {
      return this.potatoesService.getPotatoeList(false).pipe(
        switchMap(potatoeList => {
          const FriesIds: string[] = this.getUniqueFriesIds(potatoeList);
          return this.friesService.findPeoplesName(FriesIds).pipe(
            map(Fries => {
              Fries = this.mapFriesResponse(Fries);
              const mappedPotatoes = potatoeList.map(potatoe => this.mapPotatoe(potatoe, Fries));
              return new PotatoesActions.LoadMorePotatoesSuccessAction({
                data: mappedPotatoes,
                hasMore: potatoeList.length === SB_MAX_Potatoes_COUNT
              });
            }),
            catchError(err => {
              logErrorAndNotifyUser(this.notificationService, Potatoes_ERRORS.LOAD_MORE_Potatoes, err);
              return observableOf(new PotatoesActions.LoadMorePotatoesFailAction(err));
            })
          )
        }),
        catchError(err => {
          logErrorAndNotifyUser(this.notificationService, Potatoes_ERRORS.LOAD_MORE_Potatoes, err);
          return observableOf(new PotatoesActions.LoadMorePotatoesFailAction(err));
        })
      )
    })
  );