Angular 6 / NGRX组合减速器

app.module.ts

import { BrowserModule } from '@angular/platform-browser';
    import { NgModule } from '@angular/core';

    import { StoreModule } from '@ngrx/store';
    import { EffectsModule } from '@ngrx/effects';

    import { StoreDevtoolsModule } from '@ngrx/store-devtools';

    import { AppComponent } from './app.component';
    import counterEffects from './store/counter/counter.effects';

    import reducers from './store/reducers';

    @NgModule({
      declarations: [AppComponent],imports: [
        BrowserModule,StoreModule.forRoot(reducers),EffectsModule.forRoot([counterEffects]),StoreDevtoolsModule.instrument({
          maxAge: 10,}),],providers: [],bootstrap: [AppComponent],})
    export class AppModule {}

reducers.ts

import { combineReducers } from '@ngrx/store';
import { reducer as counterReducer,key as counterKey } from './counter';
import { reducer as profileReducer,key as profileKey } from './profile';

const appReducer = combineReducers({
  [counterKey]: counterReducer,[profileKey]: profileReducer,});

export default (state,action) => {
  if (action.type === 'REDIRECT_TO_EXTERNAL') {
    state = undefined;
  }

  return appReducer(state,action);
};

我的减速机是标准的减速机,没什么特别的.

来自React / Redux背景,我会像这样设置多个reducers,但是在Angular中,当我尝试从商店中选择时,我得到了未定义.当我尝试使用开发工具查看商店时,我看不到我的减速器和状态都不是{}

如何在Angular 6 / NgRX 4中设置多个减速器？