javascript - 使用 Lodash 展平对象数组并通过重复日期获取唯一键和值？

Question

我一直在尝试 Lodash，但还没有接近一个不涉及大量额外循环和开销的解决方案。

data: [
    {
      name: "FirstResult", values: [
        {
          value: { NameCount: 1, OtherCount: 1 },
          date: 2019-05-15T07:00:00+0000
        },
        {
          value: { NameCount: 1 },
          date: 2019-05-16T07:00:00+0000
        }
      ]
    },
    {
      name: "SecondResult",
      values: [
        {
          value: { NameCount: 1 },
          date: 2019-05-15T07:00:00+0000
        },
        {
          value: { BuyCount: 2, SellCount: 1 },
          date: 2019-05-16T07:00:00+0000
        }
      ]
    }
  ]

我想将其展平并通过使用日期作为返回一些配置的键来组合和聚合它，例如:

[ 
  { date: 2019-05-15T07:00:00+0000, values: { NameCount: 2, OtherCount: 1 } },
  { date: 2019-05-16T07:00:00+0000, values: { NameCount: 1, BuyCount: 2, SellCount: 1 } }
]

或者甚至只是一个平面对象数组也可以，例如:

[ 
  { date: 2019-05-15T07:00:00+0000, NameCount: 2, OtherCount: 1 },
  { date: 2019-05-16T07:00:00+0000, NameCount: 1, BuyCount: 2, SellCount: 1 }
]

有人对如何使用 Lodash 或 Vanilla 解决方案做到这一点有任何想法吗？

Answer 1

您可以使用 lodash 的链来展平、按日期分组，然后将每个组映射并合并到单个对象:

const fn = data => _(data)
  .flatMap('values') // flatten to array of objects
  .groupBy(o => o.date.toISOString()) // group by the iso representation 
  .map(group => { // map the groups by merging, and converting to require format
    const { date, value } = _.mergeWith({}, ...group, (objValue, srcValue) =>
      _.isNumber(objValue) ? objValue + srcValue : undefined // combine numeric values
    )
    
    return {
      date,
      ...value,
    }
  })
  .value()

const data = [{"name":"FirstResult","values":[{"value":{"NameCount":1,"OtherCount":1},"date": new Date("2019-05-15T07:00:00.000Z")},{"value":{"NameCount":1},"date": new Date("2019-05-16T07:00:00.000Z")}]},{"name":"SecondResult","values":[{"value":{"NameCount":1},"date":new Date("2019-05-15T07:00:00.000Z")},{"value":{"BuyCount":2,"SellCount":1},"date": new Date("2019-05-16T07:00:00.000Z")}]}]

const result = fn(data)

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

或者您可以使用 _.flow() 生成函数 ( I'm using lodash/fp here ):

const { flow, flatMap, groupBy, map, mergeAllWith, cond, isNumber, add } = _

const fn = flow(
  flatMap('values'), // flatten to array of objects
  groupBy(o => o.date.toISOString()), // group by the iso representation
  map(mergeAllWith(cond([[isNumber, add]]))), // combine numeric values
  map(({ date, value }) => ({ date, ...value })) // format the objects
)

const data = [{"name":"FirstResult","values":[{"value":{"NameCount":1,"OtherCount":1},"date": new Date("2019-05-15T07:00:00.000Z")},{"value":{"NameCount":1},"date": new Date("2019-05-16T07:00:00.000Z")}]},{"name":"SecondResult","values":[{"value":{"NameCount":1},"date":new Date("2019-05-15T07:00:00.000Z")},{"value":{"BuyCount":2,"SellCount":1},"date": new Date("2019-05-16T07:00:00.000Z")}]}]

const result = fn(data)

console.log(result)

<script src='https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.min.js)'></script>