NGRX

Question

当其中一个需要 props 时，如何组合 reducer？

我有以下型号：

interface Device {
  id: string;
  data: IDeviceData;
}

和如下所示的 DeviceReducer：

import { EntityState, EntityAdapter, createEntityAdapter } from '@ngrx/entity';
import { Device } from '../model/device';
import { SubnetBrowserApiActions } from 'src/app/explorer/actions';

export interface State extends EntityState<Device> { }

export const adapter: EntityAdapter<Device> = createEntityAdapter<Device>();

export const initialState: State = adapter.getInitialState();

export function reducer(
  state = initialState,
  action:
    | SubnetBrowserApiActions.SubnetBrowserApiActionsUnion
): State {
  switch (action.type) {
    case SubnetBrowserApiActions.SubnetBrowserApiActionTypes.LoadEntriesSucces: {
      return adapter.upsertMany(action.payload.entries, state);
    }

    default: {
      return state;
    }
  }
}

const {
  selectAll,
} = adapter.getSelectors();

export const getAllDevices = selectAll;

在我的另一个减速器中，当我想 select 使用 id 数组的设备时，我使用以下代码：

export const getVisibleDrives = createSelector(
  [fromRoot.getAllDevices, getVisibleDrivesSerialNumbers],
  (devices, visibleDevicesIds) =>
    devices.filter((device) => onlineDevicesIds.includes(device.serialNumber)),
);

这段代码非常重复，所以我想添加参数化 select 或者这将 return 只有这些驱动器，它们在我作为道具传递的数组中具有 id。我尝试做的事情如下所示：

附加select或 DeviceReduced

export const getDrivesWithIds = (ids: string[]) => createSelector(
  getAllDevices,
  devices => devices.filter(device => ids.includes(device.id))
);

然后按以下方式组合它们：

export const getVisibleDrives = createSelector(
  getVisibleDrivesSerialNumbers,
  (ids) => fromRoot.getDrivesWithIds
);

这里的问题是这个 select 的 returned 类型或者是

(ids: string[]) => MemoizedSelector<State, Device[]>

这让我无法用这个 selector 做任何有用的事情。例如，我想按关键字过滤此列表，但我无法在其上使用 filter 方法：

用法示例

export const getFilteredVisibleDrives = createSelector(
  [getVisibleDrives, getKeywordFilterValue],
  (visibleDrives, keywordFilter) => {
    return visibleDrives
      .filter(drive => // in this line there is an error: Property 'filter' does not exist on type '(ids: string[]) => MemoizedSelector<State, Device[]>'
        drive.ipAddress.toLowerCase().includes(keywordFilter.toLowerCase()) ||
        drive.type.toLowerCase().includes(keywordFilter.toLowerCase()) ||
        drive.userText.toLowerCase().includes(keywordFilter.toLowerCase())
      );
  },
);

Answer 1

看我的postNgRx: Parameterized selectors 获取更多信息。

更新：NgRx v13+

带道具的选择器已弃用，请改用选择器工厂：

选择器：

export const getCount = (props: {id: number, multiply:number}) =>   
  createSelector(     
    (state) => state.counter[props.id],     
    (counter) => counter * props.multiply
  );

组件：

this.counter2 = this.store.pipe(
  select(fromRoot.getCount({ id: 'counter2', multiply: 2 })
);   
this.counter4 = this.store.pipe(
  select(fromRoot.getCount({ id: 'counter4', multiply: 4 })
);

已弃用

选择器：

export const getCount = () =>   
  createSelector(     
    (state, props) => state.counter[props.id],     
    (counter, props) => counter * props.multiply
  );

组件：

this.counter2 = this.store.pipe(
  select(fromRoot.getCount(), { id: 'counter2', multiply: 2 })
);   
this.counter4 = this.store.pipe(
  select(fromRoot.getCount(), { id: 'counter4', multiply: 4 })
);

NGRX - 结合选择器和道具

NGRX - combine selectors with props

ngrx-store

更新：NgRx v13+

已弃用