ngrx/effects 没有 HttpHandler 的提供程序

Question

我正在尝试重新创建一个与 ngrx docs 非常相似的 authEffect，但收到此错误消息： Error: StaticInjectorError(AppModule)[HttpClient -> HttpHandler]: StaticInjectorError(Platform: core)[HttpClient -> HttpHandler]: NullInjectorError: No provider for HttpHandler!

效果服务：

@Injectable()
export class HttpEffects {
  constructor(private http: HttpClient, private actions$: Actions) {}

  @Effect() login$: Observable<ActionWithPayload> = this.actions$.pipe(
    ofType(ActionTypes.SEND_LOGIN),
    mergeMap((action: ActionWithPayload) =>
      this.http.post(SERVER_URL + LOGINAPI.LOGIN, action.payload, config).pipe(
        map(data => ({type: 'LOGIN_SUCCESS', payload: data})),
        catchError(() => of({type: 'LOGIN_ERROR'}))
      ))
  );
}

app.module:

@NgModule({
  declarations: [
    AppComponent,
  ],
  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    StoreModule.forRoot(rootReducer),
    StoreDevtoolsModule.instrument({
      maxAge: 10
    }),
    EffectsModule.forRoot([HttpEffects])
  ],
  exports: [
    BrowserAnimationsModule
  ],
  providers: [ HttpClient ],
  bootstrap: [AppComponent]
})

我也尝试过在特征模型中导入效果服务，EffectsModule.forFeature()，但抛出同样的错误。

Answer 1

如HttpClient documentation所述：

Before you can use the HttpClient, you need to install the HttpClientModule which provides it. This can be done in your application module, and is only necessary once.

所以你必须导入 HttpClientModule 而不是 HttpClient:

import { HttpClientModule } from '@angular/common/http';

@NgModule({
  declarations: [
    AppComponent,
  ],
  imports: [
    BrowserModule,
    HttpClientModule,
    ...
    EffectsModule.forRoot([HttpEffects])
  ],
  exports: [
    BrowserAnimationsModule
  ],
  bootstrap: [AppComponent]
})

ngrx/effects 没有 HttpHandler 的提供程序

No provider for HttpHandler with ngrx/effects

angular

angular5

ngrx

ngrx-effects