ES6 Group By和SUM的实现 [英] ES6 Implementation of Group By and SUM

问题描述

我有一个具有以下属性的对象数组:material_no，material_name，qty.

I have an array of objects with these properties: material_no, material_name, qty.

let data = [
  { material_no: '1001', material_name: 'Material 1', qty: 100 },
  { material_no: '1001', material_name: 'Material 1', qty: 50 },
  { material_no: '1002', material_name: 'Material 2', qty: 44 },
  { material_no: '1003', material_name: 'Material 3', qty: 125 },
  { material_no: '1002', material_name: 'Material 2', qty: 59 },
  { material_no: '1004', material_name: 'Material 4', qty: 999 },
  { material_no: '1005', material_name: 'Material 5', qty: 80 },
  { material_no: '1005', material_name: 'Material 5', qty: 66 }
]

如何返回按其material_no/material_name和具有相同material_no/material_name的数量的总和分组的对象数组?

How do I return an array of objects grouped by their material_no/material_name and sum of the qty having the same material_no/material_name?

[
  { material_no: '1001', material_name: 'Material 1', qty: 150 },
  { material_no: '1002', material_name: 'Material 2', qty: 103 },
  { material_no: '1003', material_name: 'Material 3', qty: 125 },
  { material_no: '1004', material_name: 'Material 4', qty: 999 },
  { material_no: '1005', material_name: 'Material 5', qty: 146 }
]

推荐答案

您可以将数组简化为 Map ，按 material_no 存储总项.然后只需将映射值提取到数组即可.

You could reduce array to a Map that stores total items by material_no. And then just extract map values to array.

let data = [
  { material_no: '1001', material_name: 'Material 1', qty: 100 },
  { material_no: '1001', material_name: 'Material 1', qty: 50 },
  { material_no: '1002', material_name: 'Material 2', qty: 44 },
  { material_no: '1003', material_name: 'Material 3', qty: 125 },
  { material_no: '1002', material_name: 'Material 2', qty: 59 },
  { material_no: '1004', material_name: 'Material 4', qty: 999 },
  { material_no: '1005', material_name: 'Material 5', qty: 80 },
  { material_no: '1005', material_name: 'Material 5', qty: 66 }
]

const sums = [
  ...data.reduce(
    (map, item) => {
      const { material_no: key, qty } = item;
      const prev = map.get(key);
      
      if(prev) {
        prev.qty += qty
      } else {
        map.set(key, Object.assign({}, item))
      }
      
      return map
    },
    new Map()
  ).values()
]

console.log(sums)

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