我已经查看了与此相关的另外 2 篇文章,其中一个包含较大状态的文章不适用,而另一篇则注册了多个 forFeature - 我已经对此进行了一些测试,即使我在之前或之后导入它我的 app.module 中的 forRoot(reducers) 没有什么区别。
我确信我在配置中遗漏了一些明显的东西。
我的配置:
export const orderAdapter: EntityAdapter<IOrder> = createEntityAdapter<IOrder>({
selectId: (order: IOrder) => order._id
});
export interface AllOrdersState extends EntityState<IOrder> {}
export const initialState: AllOrdersState = orderAdapter.getInitialState({
ids: [],
entities: {}
});
export const OrdersState = createFeatureSelector<AllOrdersState>('orders');
export const {
selectIds,
selectEntities,
selectAll,
selectTotal
} = orderAdapter.getSelectors(OrdersState);
我的实际减速器:
export function ordersReducer(
state: AllOrdersState = initialState,
action: actions.OrdersActions
) {
case actions.CREATE_MANY: {
console.log(action.orders);
return orderAdapter.addMany(action.orders, state);
}
}
我在我的 Order.Module 中注册为:
StoreModule.forFeature('orders', ordersReducer),
我的主减速器图:
const reducers: ActionReducerMap<AppState> = {
order: orderReducer,
admin: adminReducer,
tlabs: tlabsReducer,
reports: reportsReducer,
settings: settingsReducer,
orders: ordersReducer
};
然后是app.module中的主要导入:
StoreModule.forRoot(reducers),
尝试读取实体:
构造者:
private store: Store<AppState>
实际功能:
this.store
.select(ordersReducer.selectAll)
导入来源:
import * as ordersReducer from '../../../../../store/reducers/orders.reducer';
我遇到此错误是因为我使用错误的功能键设置选择器:
export const selectIocState = createFeatureSelector<fromIoc.IocState>('this_key_was_wrong');
它应该与您在功能模块中加载的内容相匹配:
StoreModule.forFeature('feature_key', iocReducer),
我在entity.js(NGRX实现文件)中遇到了与您类似的错误。就我而言,我有一个延迟加载的模块,其自己的状态最初是未定义的。由于实体选择器在获取实体相关字段(例如 ids)之前不执行任何 null 检查,因此会导致此错误。我的解决方案是避免使用
orderAdapter.getSelectors(OrdersState)
,而是定义我自己的受保护选择器,这非常简单:
export const selectIds = createSelector(selectOrderState, (state) => state?.ids);
export const selectEntities = createSelector(selectOrderState, (state) => state?.entities);
export const selectAll = createSelector(selectOrderState, (state) => (state?.ids as Array<string|number>)?.map(id => state?.entities[id]));
export const selectTotal = createSelector(selectOrderState, (state) => state?.ids?.length);
我不喜欢我没有使用内置选择器,但至少这不会破坏我的代码。我希望 NGRX 团队提供一种方法来避免此类情况。
看起来它正在尝试在初始化之前从
OrdersState
读取。您的减速器实际上并不返回默认状态以对其进行初始化;而是返回默认状态。至少在你提供的代码中你似乎没有。
让你的reducer返回默认状态。
export function ordersReducer(
state: AllOrdersState = initialState,
action: actions.OrdersActions
) {
switch(action.type) {
case actions.CREATE_MANY: {
console.log(action.orders);
return orderAdapter.addMany(action.orders, state);
}
default: {
return state // Here you should return the default state
}
}
}
当我忘记添加“state”作为adapter.addOne()的第二个参数时,我遇到了同样的错误。因此,在 OP 示例中,如果 redcuer 是按以下方式编写的:
return orderAdapter.addMany(action.orders); // !! lack of "state" as 2nd param
那么错误将完全相同。就我而言,这是:
Uncaught TypeError: Cannot read properties of undefined (reading 'ids')
at Object.operation [as addOne] (entity.js?9b56:59:1)
at eval (eval at <anonymous> (mapping-fields-group.reducer.ts?fd4f:1:1), <anonymous>:1:17)
at eval (mapping-fields-group.reducer.ts?fd4f:13:1)
at eval (store.js?d450:1204:1)
at combination (store.js?d450:215:1)
at mappingsDataReducers (mappings-data-state.ts?7c86:21:1)
at eval (store.js?d450:265:1)
at combination (store.js?d450:215:1)
at eval (store.js?d450:254:1)
at computeNextEntry (store-devtools.js?777a:445:1)
对于那些在运行时遇到这个问题的人
ng test
,我收到此错误,因为我需要设置一个模拟商店和模拟选择器进行测试。
有关如何设置测试模拟的详细信息,请参阅NgRx 测试 > 使用模拟选择器文档。
这是我在测试中如何实现这一点的示例:
describe('DataManagerService', () => {
let service: DataManagerService;
let store: MockStore;
beforeEach(() => {
TestBed.configureTestingModule({
imports: [HttpClientTestingModule],
providers: [
provideMockStore({
selectors: [{
selector: myEntityFeature.selectAll,
value: [{id: 1, name: 'Mock Entity'}],
};],
}),
],
});
service = TestBed.inject(DataManagerService);
store = TestBed.inject(MockStore);
});
it('should be created', () => {
expect(service).toBeTruthy();
});
});
注意:我使用 NgRx 原理图生成实体、操作、减速器和效果作为特征。因此,在我定义选择器名称
myEntityFeature.selectAll
的行中,您需要将其替换为对实际选择器的引用。同样, value
应替换为与选择器中定义的接口匹配的模拟对象。