更新嵌套Redux reducer對象的值

Question

我有一個關於Redux和更新嵌套對象的值的問題。

假設這是我的初始狀態：

const INITIAL_STATE = {
 columnState: {
  1: {
    loading: false
  },
  2: {
    loading: false
  }
 }
};

當我的減速器被調用時：

case COLUMN_STATE_UPDATE:
    const { type } = payload;
    return {
       ...state
    }
}

如何更新特定ID的loading值？ 假設我用鍵= 2更新了條目，如何使用鍵2將columnState對象的loading值更改為true ，並返回新狀態？

Answer 1

如果您的COLUMN_STATE_UPDATE操作僅更新columnState部分（假定payload中的type為鍵）：

case COLUMN_STATE_UPDATE:
    const { type } = payload;
    return {
       ...state,                     // keep the other keys as they were
       [type]: {                     // only update the particular one
           loading: true 
       }
    }
}

---

如果您的COLUMN_STATE_UPDATE操作正在更新看起來像INITIAL_STATE的整個狀態（同樣，假設payload中的type為鍵）：

case COLUMN_STATE_UPDATE:
    const { type } = payload;
    return {
       ...state,                     // keep the other keys of state as they were
       columnState: {
           ...state.columnState,     // keep the other keys of columnState as they were
           [type]: {                 // only update the particular one
               loading: true
           }
       }

    }
}

Answer 2

case COLUMN_STATE_UPDATE:
// payload = {type: 1, 1: {loading: true}}
    const {type} = payload;
    return {
       columnState: {...state.columnState, [type]: payload[type] }}
};

以上可以實現為：

/**
   * @param {Object} state The Global State Object of shape:
   * @example
   * const INITIAL_STATE = {
   *     columnState: {
   *         1: {
   *             loading: false
   *         },
   *         2: {
   *             loading: false
   *         }
   *     }
   * };
   * @param {Object} action The Action Object of shape
   * @example 
   * let action = {type: 1, 1: {loading: true}};
   * @returns {Function} The "slice reducer" function.
   */

function columnStateUpdate(state = {}, action) {
    const {type} = action;
    switch(type) {
        case COLUMN_STATE_UPDATE:   
        return {
            columnState: {...state.columnState, [type]: action[type] }}
        };
    }
}

我使用action而不是payload因為(state, action)是Redux Docs中使用的標准命名約定