javascript - 重新选择 - 在 createSelector 中为第二个选择器使用自定义参数

Question

我有以下案例:

const firstSelector = (store, userId) => { ... };
const secondSelector = (store, moneyId) => { ... };

const selector = createSelector(
   firstSelector,
   secondSelector, // it doesn't accept `userId` but `moneyId` which is inside 
                   // `firstSelector` (first.moneyId)
   (first, second) => { ... },
);

如您所见，如果我可以将自定义参数传递给第二个选择器，一切都会很棒。

这个 secondSelector 接受 moneyId 作为第二个参数，实际上它是 first.moneyId。

我能否在第二个组合选择器上使用参数，这实际上是 firstSelector 返回的值？

Answer 1

const firstSelector = (store, userId) => ({ moneyId: 'moneyIdFromFirst' });
const secondSelector = (store, moneyId) => ({ second: 'selector', moneyId });

const intermediateSelector = (store, userId) => createSelector(
  firstSelector,
  (first) => secondSelector(store, first.moneyId)
)(store, userId)

const selector = createSelector(
  firstSelector,
  intermediateSelector,
  secondSelector, // not longer necessary
  (first, second, third) => 
    console.log(first, second, third)
);

实现输出:

Object { moneyId: "moneyIdFromFirst" }
Object { second: "selector", moneyId: "moneyIdFromFirst" }
Object { second: "selector", moneyId: "userId" }

intermediateSelector 返回值 moneyIdFromFirst 而不是 secondSelector 的 userId。

感谢@Joseph Sikorski，您可以使用简约的单功能解决方案:

const selectorOneFunc = createSelector(
  firstSelector,
  (state, userId) =>
    secondSelector(state, firstSelector(state, userId).moneyId),
  (first, second) =>
    console.log("selectorOneFunc:", first, second)
);