NGRX嵌套Feature时自动生成Selector失效问题求助

一、无需手动重定义所有选择器的方案 #

自动生成的选择器默认从根State的对应Feature节点取值，当Feature嵌套在子State下时，只需重新指定该Feature的根选择器路径即可：

1. 先创建substate1的根选择器：

// 推荐用createFeature创建substate1，自动生成根选择器
export const substate1Feature = createFeature({
  name: 'substate1',
  reducer: combineReducers({
    feature1: feature1.reducer,
    feature2: feature2.reducer,
  }),
});
export const selectSubstate1 = substate1Feature.selectSubstate1;

2. 重写feature1的selectFeatureState（自动生成选择器的基础）：

// 让feature1的根选择器指向substate1下的feature1节点
feature1.selectFeatureState = createSelector(
  selectSubstate1,
  (state) => state.feature1
);

完成后，原来自动生成的feature1.selectA、feature1.selectB就能正常从嵌套路径取值，无需逐个重定义。

二、手动组合选择器的方案（若上述方法不适用） #

如果需要单独编写目标选择器，可以复用自动生成的feature1.selectA，步骤如下：

1. 先创建substate1的根选择器（同上述步骤1）：

export const substate1Feature = createFeature({
  name: 'substate1',
  reducer: combineReducers({
    feature1: feature1.reducer,
    feature2: feature2.reducer,
  }),
});
export const selectSubstate1 = substate1Feature.selectSubstate1;

2. 编写组合选择器，复用自动生成的选择器：

export const selectFeature1A = createSelector(
  // 先获取substate1下的feature1节点
  createSelector(selectSubstate1, (state) => state.feature1),
  // 直接复用feature1自动生成的selectA
  feature1.selectA
);

或者更简洁的写法：

export const selectFeature1A = createSelector(
  selectSubstate1,
  (substate1) => feature1.selectA(substate1.feature1)
);

内容的提问来源于stack exchange，提问作者mariusr