如何分配新的键值对而不覆盖顶级键?

本文介绍了如何分配新的键值对而不覆盖顶级键?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

如何在嵌套对象中添加键/值对而不覆盖Redux reducer中的顶级键?

How do I add a key/value pair to a nested object without overwriting the top level keys in my Redux reducer?

注释之前的状态:

notes: {
  -KQpqwDTyLOzd-8UXi-z: {
    created: 1473035305252,
    text: 'stuff',
  }
  -KQqe4xiwV4-5WIs2Gpg: {
    created: 1473017044898,
    text: 'more stuff',
  }
}

在以下位置注明状态:

notes: {
  0: {
    created: 1473035305252,
    text: 'stuff',
    new: 'new value',
  }
  1: {
    created: 1473017044898,
    text: 'more stuff',
  }
}

这是我的减速器，可产生以上结果:

here is my reducer that is producing the above results:

import _ from 'lodash'

const notes = (state = [], action) => {
  switch (action.type) {
    case 'FETCH_NOTES':
      return action.payload;
    case 'CLEAR_NOTES':
      return state = [];
    case 'UPDATE_NOTE':
      console.log(state)
      return _.map(state, (note, index) => {
        if (index === action.id) {
          return _.assign({}, note, {
            new: action.new
          })
        }
        return note
      })
    default:
      return state
  }
}
export default notes

推荐答案

请使用 mapValues 函数代替 map 功能.下面更新了代码.

Please use mapValues function instead of map function. Updated code below.

return _.mapValues(state, (note, index) => {
    if (index === action.id) {
      return _.assign({}, note, {
        new: action.new
      })
    }
    return note
  })

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