ERROR TypeError: Cannot read property 'pipe' of null in NGRX Effect

Question

当我在我的组件中调度我的动作时，应该触发这个 updateTour 效果。但是这个错误出现在我的浏览器控制台 core.js:5847 ERROR TypeError: Cannot read property 'pipe' of null at SwitchMapSubscriber.project (updatetour.effects.ts:87) requestHandlerService.invoke(request).pipe 导致错误。谁能解释一下这里出了什么问题

updataTour$ = createEffect(() =>
   this.actions$.pipe(
       ofType(TourproviderAction.updateTourprovider),
       switchMap((action) => {
       const data = action.tourProvider;
       const parameters: any = { tourProviderId: '1' };
       const queryParams = new HttpParams({
              fromObject: parameters
       })

        const options = {
                params: queryParams,
                headers: {
                    'Content-Type': 'application/json',
                    'Authorization': 'a5sfjdksfjksfe2f4af3673ce1a'
              }
         };

        const request = new ServiceRequest
       (environment.urls.tourProvider, 'POST', formData, options);
        return this.requestHandlerService.invoke(request).pipe(
                map((updateResponce) => {
             const responceData = JSON.stringify(updateResponce)
             return TourproviderAction.updateTourproviderSuccess({ responce: responceData });
                }),
                catchError(err => {
                    const errorMessage = JSON.stringify(err);
                    return of(TourproviderAction.updateTourproviderFail({ errorMessage }))
                })
            );
        })
    )
);

Answer 1

错误的意思是这一行

this.requestHandlerService.invoke(request)

为 returning null，无法调用管道函数。确保您 return 可从调用方法中观察到，以便您可以通过管道传输响应。

Answer 2

确保requestHandlerService.invoke（请求）returns Observables

ERROR TypeError: Cannot read property 'pipe' of null in NGRX Effect

ERROR TypeError: Cannot read property 'pipe' of null in NGRX Effect

angular

ngrx

ngrx-effects