Question

我目前正在开发一个简单的测试应用程序，以了解有关@ ngrx / store的更多信息。我有一个名为TrainingModule的模块，它应该存储一些练习和更多信息。代码有效，但我试着在这里改进。我目前拥有的是我的功能模块，如下所示：

@NgModule({
  imports: [
    CommonModule,
    TrainingRoutingModule,
    StoreModule.forFeature('exercises', exerciseReducer)
  ],
  declarations: [
    TrainingDashboardComponent,
    TrainingCoreComponent,
    TrainingNavComponent,
    TrainingPlanComponent,
    ExerciseOverviewComponent,
    ExerciseListComponent]
})
export class TrainingModule {
}

和我的减速机看起来像那样：

export interface ExerciseState {
  exercises: IExercise[];
}

export interface State extends fromRoot.State {
  'exercises': ExerciseState;
}

export const initialState: ExerciseState = {
  exercises: [
    {id: 1, name: 'Exc 1'},
    {id: 2, name: 'Exc 2'}
  ]
};

export function exerciseReducer(state: ExerciseState = initialState, action: any): ExerciseState {
  switch (action.type) {
    default:
      return state;
  }
}

export const getExerciseState = createFeatureSelector<ExerciseState>('exercises');
export const getExercises = createSelector(getExerciseState, state => state.exercises);

到目前为止一切顺利。在我的模板中，我使用

从商店中选择我的练习

exercise$: Observable<IExercise[]>;

  constructor(private store: Store<State>) { }

  ngOnInit() {
    this.exercise$ = this.store.select(getExercises);
  }

所以我现在要做的就是将我的减速器组合在一起，这样我就不必像这样添加每个减速器了

StoreModule.forFeature('exercises', exerciseReducer);
StoreModule.forFeature('sample', sampleReducer);
StoreModule.forFeature('sample1', sampleReducer1);

在我的所有模块中。我试图用

收集所有减速器

export const trainingReducers = {
  'exercise': exerciseReducer
};

和

StoreModule.forFeature('training', trainingReducers)

但是这给了我一个无法在控制台中读取未定义错误消息的属性'练习'。也许有人可以帮助我理解，我如何从特征模块中收集所有减少器并为其创建一个正确的选择器。

Answer 1

我可以举个例子来说明我是怎么做到的。我使用index.ts来捆绑模块中的所有其他reducer，如下所示：

模块/减速器/ index.ts

import * as fromRoot from '../../../reducers';
import * as fromSearch from './search';
import * as fromUserDetail from './user-detail';
import * as fromDetailBase from './base';


export interface UserModuleState {
  search: fromSearch.State;  
  detail: fromUserDetail.State;
  detailBase: fromDetailBase.State;
}

export interface State extends fromRoot.State {
    userModule: UserModuleState;    
}

export const reducers = {    
    search: fromSearch.reducer,
    detail: fromUserDetail.reducer,
    detailBase : fromDetailBase.reducer
};

export const selectUserModuleState = createFeatureSelector<UserModuleState>('userModule');


export const selectSearchState = createSelector(
    selectUserModuleState, (state: UserModuleState) => state.search
);
export const getSearchLoading = createSelector(selectSearchState, fromSearch.getLoading);
export const getSearchEntities = createSelector(selectSearchState, fromSearch.getEntities);

模块/ user.module.ts

import { reducers } from './reducers';
@NgModule({
    imports: [
        ...
        StoreModule.forFeature('userModule', reducers)
    ],
     ...
})
export default class UserModule { }

Answer 2

您的设置几乎正确。

在createFeatureSelector函数中，您在商店的根目录中声明了功能键，在示例中为'exercises'。因此，例如，您将选择store.exercises.exercises.id，而功能选择器只是store.exercises的快捷方式。

但是，在StoreModule.forFeature('training', trainingReducers)调用中，您将“培训”定义为功能模块的根密钥。

正确的设置如下所示：

export const featureReducersMap = {
  exercise: exerciseReducer,
  anyOtherKey: anyOtherReducer
};

StoreModule.forFeature('myFeatureModule', featureReducersMap);

export interface FeatureState{
  exercise: string;
  anyOtherKey: number;
}

然后编写如下选择器：

export const featureSelector = createFeatureSelector<FeatureState>('myFeatureModule');

export const exerciseSelector = createSelector(
  featureSelector,
  (state: FeatureState) => state.exercise
);

建议将功能键存储在变量中，而不是对其进行硬编码。

@ ngrx / store结合了功能模块中的多个Reducer

2 个答案: