Use reselect selector with parameters

问题:

How do I pass additional parameters to combined selectors? I am trying to

• Get data

• Filter data

• Add custom value to my data set / group data by myValue

export const allData = state => state.dataTable
export const filterText = state => state.filter.get('text')

export const selectAllData = createSelector(
  allData,
  (data) => data
)

export const selectAllDataFiltered = createSelector(
  [ selectAllData, filterText ],
  (data, text) => {
    return data.filter(item => {
      return item.name === text
    })
  }
)

export const selectWithValue = createSelector(
  [ selectAllDataFiltered ],
  (data, myValue) => {
    console.log(myValue)
    return data
  }
)

let data = selectWithValue(state, 'myValue')

console.log(myValue) returns undefined

回答1:

The answer to your questions is detailed in an FAQ here: https://github.com/reactjs/reselect#q-how-do-i-create-a-selector-that-takes-an-argument

In short, reselect doesn't support arbitrary arguments passed to selectors. The recommended approach is, instead of passing an argument, store that same data in your Redux state.

回答2:

what about returning a function from selector? getFilteredToDos is an example for that

// redux part
const state = {
  todos: [
    { state: 'done',     text: 'foo' },
    { state: 'time out', text: 'bar' },
  ],
};

// selector for todos
const getToDos = createSelector(
  getState,
  (state) => state.todos,
);

// selector for filtered todos
const getFilteredToDos = createSelector(
  getToDos,
  (todos) => (todoState) => todos.filter((toDo) => toDo.state === todoState);
);

// and in component
const mapStateToProps = (state, ownProps) => ({
  ...ownProps,
  doneToDos: getFilteredToDos()('done')
});

回答3:

Another option:

const parameterizedSelector = (state, someParam) => createSelector(
  [otherSelector],
  (otherSelectorResult) => someParam + otherSelectorResult
);

And then use like

const mapStateToProps = state => ({
  parameterizedSelectorResult: parameterizedSelector(state, 'hello')
});

I am not sure about memoization/performance in this case though, but it works.