为什么应用程序 redux 在此减速器中有错误？

Question

Why app redux have error in this reducer? what have I not done? and where exactly?how to fix it? Tell me please Tell me please reducer:

import { searchFilter } from '../components/app';
     function reducer (state = {}, action) {

        switch (action.type) {
          case 'SET_SHIFT':
             return Object.assign({} {
                shift: action.shift
             });
          case 'SET_SEARCH':
             return Object.assign({} {
                search: action.search.toLowerCase()
             });
          case 'RUN_FILTER':
             return Object.assign({} {
                shift: action.shift || state.shift,
                search: action.search || state.search,
                filteredData: searchFilter(state.search, state.data[state.shift])
             });
          case 'LOAD_DATA_START':
             return Object.assign({}{
                day: action.day
             });
          case 'LOAD_DATA_END':
             return Object.assign({} {
                data: action.data,
                shift: Object.keys(action.data)[0],
                filteredData: searchFilter(state.search, state.data[state.shift])
             });
       }
    }

    export default reducer;    

Answer 1

The main problem I see is you do not return the new state from your reducer.

A reducer should be a pure function wich, given a state and an action, returns a new state.

put return state at the bottom of your reducer.

Answer 2

There's a lot going on in your example, I'd strip it back a bit (especially getting rid of middleware and thunk), get a handle on the basic Redux model and then build it out again.

Your reducer should look something like this:

 import { searchFilter } from '../components/app';
 function reducer (state = {}, action) {

    switch (action.type) {
      case 'SET_SHIFT':
         //no need for break on return
         return Object.assign({}, state, {
            shift: action.shift
         });
      case 'SET_SEARCH':
         return Object.assign({}, state, {
            search: action.search.toLowerCase()
         });
      case 'RUN_FILTER':
         return Object.assign({}, state, {
            shift: action.shift || state.shift,
            search: action.search || state.search,
            filteredData: searchFilter(state.search, state.data[state.shift])
         });
      case 'LOAD_DATA_START':
         return Object.assign({}, state, {
            day: action.day
         });
      case 'LOAD_DATA_END':
         return Object.assign({}, state, {
            data: action.data,
            shift: Object.keys(action.data)[0],
            filteredData: searchFilter(state.search, state.data[state.shift])
         });
      //then you definitely need to have this
      default:
         return state;
   }
}

export default reducer;    

Can I recommend you put some console.log statements in your reducer so you can see the data is being put into the Redux store as expected?