Angular 9- NGRX如何注册“全局”缩减器

Question

假设我有一个状态AnimalState，如下所示：

{
  cats: Cat[];
  dogs: Dog[];
}

下面是如何定义reducers的：

export const catsReducer = createReducer([],
  on(AnimalAction.loadCats,
    (state, { cats }) => {
      return {
        ...state,
        cats
      };
    }),
);

export const dogsReducer = createReducer([],
  on(AnimalAction.loadDogs,
    (_, { dogs }) => {
      return dogs;
    }),
);

export const reducers: ActionReducerMap<AnimalState> = {
  cats: catsReducer,
  dogs: dogsReducer,
};

然后，我使用InjectionToken将缩减程序注入到我的自定义模块中，如下所示：

const reducerToken = new InjectionToken<ActionReducerMap<AnimalState>>(
'ANIMAL_REDUCERS', 
{ factory: () => reducers });
StoreModule.forFeature("animal", reducerToken),

我的问题是如何创建和注册同时使用cats和dogs值的缩减程序。

Answer 1

好的，你可能会想要拆分reducer和initial状态：

const initialCatState: Cat[] = []


export const catsReducer = createReducer(initialCatState,
  on(CatAction.update,
    (state, { cats }) => {
      return cats;
    }),
);


const initialDogState: Dog[] = []


export const dogsReducer = createReducer(initialDogState,
  on(DogAction.update,
    ((state: Dog[]), { dogs }) => {
      return dogs;
    }),
  on(DogAction.add,
    ((state: Dog[]), { dog }) => {
      return [...dogs, dog];
    }),
);

然后注册两个功能：

StoreModule.forFeature("cats", catsReducer),
StoreModule.forFeature("dogs", dogsReducer),

并选择

export const selectCats = createFeatureSelector('cats');
export const selectDogs = createFeatureSelector('dogs');