javascript - 如何使用 Lodash 转换数据

Question

我对 lodash 没有太多经验，我想转换我的数据。我尝试使用 groupBy 和 map 但无法获得预期结果。如果有人可以提供帮助，我将不胜感激。

示例数据

var sample = [{
    "changeType": 1,
    "type": "changeAccount",
    "updated": {
      "id": 71,
      "company": 124201,
      "user": 8622
    }
  },
  {
    "changeType": 2,
    "type": "changeAccount",
    "updated": {
      "id": 70,
      "company": 124201,
      "user": 8622
    }
  },
  {
    "changeType": 1,
    "type": "changeproduct",
    "updated": {
      "id": 15,
      "company": 124201,
      "user": 8622
    }
  }
]

// what I tried
var result = _.mapValues(_.groupBy(sample, "type"), x => x.map(y => _.omit(y, "changeType")));

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>

预期结果

var output = [
  {
    "type": "changeAccount",
    1: [{
      "updated": 'for changeType 1 under type changeAccount
    }],
    2: [{
      "updated": for changeType 2 under type changeAccount
    }]
  },

  {
    "type": "changeProduct",
    1: [{
      "updated": for changeType 1 under type changeProduct
    }]
  }
]

预期结果2

const sample2 = [
  {type:"changeAccount", changeType: [{1:[{updated}],{2:[{updated}]}}] 
]

Answer 1

您需要_.groupBy()类型，将项目映射到对象，并通过分组获取changeType属性再次通过 changeType，映射要更新的项目，并传播结果:

const { map, groupBy, mapValues, pick } = _

const fn = arr =>
  map(groupBy(arr, 'type'), (group, type) => ({ // group and map to array of objects
    type,
    ...mapValues( // spread after mapping the values to extract updated
      groupBy(group, 'changeType'), // group again by changeType
      items => items.map(item => pick(item, 'updated') // extract the updated from each item
    ))
  }))

const sample = [{"changeType":1,"type":"changeAccount","updated":{"id":71,"company":124201,"user":8622}},{"changeType":2,"type":"changeAccount","updated":{"id":70,"company":124201,"user":8622}},{"changeType":1,"type":"changeproduct","updated":{"id":15,"company":124201,"user":8622}}]

const result = fn(sample)

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>

为了达到预期效果，您需要使用与 type 对象相同的逻辑:

const { map, groupBy, mapValues, pick } = _

const fn = arr =>
  map(groupBy(arr, 'type'), (group, type) => ({ // group and map to array of objects
    type,
    changeTypes: map( // spread after mapping the values to extract updated
      groupBy(group, 'changeType'), // group again by changeType
      (items, changeType) => ({
        changeType,
        updated: items.map(item => item.updated) // extract the updated from each item
      })
    )
  }))

const sample = [{"changeType":1,"type":"changeAccount","updated":{"id":71,"company":124201,"user":8622}},{"changeType":2,"type":"changeAccount","updated":{"id":70,"company":124201,"user":8622}},{"changeType":1,"type":"changeproduct","updated":{"id":15,"company":124201,"user":8622}}]

const result = fn(sample)

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>