angular - NGRX 影响如何将参数传递给 withLatestFrom 操作符

Question

在使用 withLatestFrom 时，我正在努力将参数传递给选择器，这是之前从加载操作有效负载映射的

loadLocalSubServices$: Observable<Action> = this.actions$.pipe(
  ofType(LocalSubServiceTemplateActions.LocalSubServicesTemplateActionTypes.LoadLocalSubService),
  map((action: LocalSubServiceTemplateActions.LoadLocalSubService) => action.payload.globalSubServiceId),
  // and below I would like to pass globalSubServiceId
  withLatestFrom(this.store.pipe(select(fromLocalSubservices.getSearchParams(globalSubServiceId)))),
  map(searchParams => searchParams[1]),
  mergeMap((params) =>
    this.subServiceService.getLocalSubServices(params).pipe(
      map(localSubServices => (new LocalSubServiceTemplateActions.LocalSubServiceLoadSuccess(localSubServices))),
      catchError(err => of(new LocalSubServiceTemplateActions.LocalSubServiceLoadFail(err)))
    )
  )
);

Answer 1

我想我有你(或 future 的流浪者)正在寻找的食谱。您必须将初始有效负载(下面的 of 运算符)映射到内部可观察对象，以便它可以通过管道传输并作为参数传递给 withLatestFrom .然后mergeMap将其展平，您可以将其作为一个数组返回给下一个运算符，并将初始负载作为第一个值。

map(action => action.payload),
mergeMap((id) =>
    of(id).pipe(
        withLatestFrom(
            this.store.pipe(select(state => getEntityById(state, id))),
            this.store.pipe(select(state => getWhateverElse(state)))
        )
    ),
    (id, latestStoreData) => latestStoreData
),
switchMap(([id, entity, whateverElse]) => callService(entity))