嵌套减速器不更新答案

【问题标题】：Nested reducers don't be updated嵌套减速器不更新
【发布时间】：2019-04-06 20:15:48
【问题描述】：

我有一个关于嵌套减速器的问题。

结构类似这样：

const INITIAL_STATE = {
    items: [],
    planningState:null,
    loading: false,
    idx_selected : '2'
};

在 state.items 中，结构是这样的：

const mockItems = [
{
    date: "2018-08-24 15:00:00",
    type: "dropoff",
    status: null,
    id: "553",
    //many others things
},
{
    date: "2018-08-24 19:00:00",
    type: "pickup",
    status: "ordered",
    id: "553",
    //other things
},
{
    date: "2018-07-18 08:00:00",
    type: "delivery",
    status: null,
    id: "554",
    //other things
},

];

我需要更改一项的状态，而不更改其他属性。我知道我必须克隆每一层，但我犯了一个错误。

case SCAN_CLOSE_DONE:
  //state.items[state.idx_selected].status=done
     return{
      ...state,
      items:{
        ...state.items,
        [state.idx_selected]:{
          ...state.items[state.idx_selected],
            status: "done"
        }
      }
    };

【问题讨论】：

标签： react-native redux nested reducers

【解决方案1】：

return {
  ...state,
  items: state.items.map(item =>
    {
      ...item,
      status: "done"
    }
  )
}

【讨论】：

【解决方案2】：

将处理该状态块的所有内容的 reducer 分解为多个 reducer，每个 reducer 处理该块的一部分。

const items = (state = [], { type, items, item, idx_selected, status }) => {
    switch(type) {
        case SCAN_CLOSE_DONE:
        const newState = [...state];
        const item = { ...newState[idx_selected], status };
        newState[idx_selected] = item;
        return newState;

        //...

        default:
            return state;
    }
};

// just examples, actual use case might be different:
const planningState = (state = null, { type, planningState }) => type === MY_ACTION ? planningState : state;
const loading = (state = null, { type, loading }) => type === ANOTHER_ACTION ? loading : state;
const idx_select = //...

export default combineReducers({
    items,
    planningState,
    loading,
    idx_select
});

【讨论】：