javascript - 如何基于动态键创建嵌套对象

Question

我需要将一些数据转换成特殊格式。棘手的部分是，它需要通过动态键进行分组和嵌套。由于原始数据是平坦的。

这是一些简化的示例数据:

const data = [
  {
    category: 'Classic',
    price: 1,
    order: '1233-ABC'
    currency: 'EUR',
  },
  {
    category: 'Classic',
    price: 2,
    order: '1234-ABC'
    currency: 'EUR',
  },
  {
    category: 'Modern',
    price: 3,
    order: '1235-ABC'
    currency: 'USD',
  },
  {
    category: 'Classic',
    price: 4,
    order: '1236-ABC'
    currency: 'EUR',
  },
  {
    category: 'Modern',
    price: 5,
    order: '1237-ABC'
    currency: 'EUR',
  },
  {
    category: 'Classic',
    price: 6,
    order: '1238-ABC'
    currency: 'USD',
  },
  {
    category: 'Modern',
    price: 7,
    order: '1239-ABC'
    currency: 'USD',
  }
];

现在我想定义分组和聚合。

例如:

grouping = ['category'];
sum = ['price'];

因此它应该按 category 键分组并汇总所有 price 键条目。

//预期输出

[{
    category: 'Classic',
    price: 13
}, {
    category: 'Modern',
    price: 15
}]

我在 reduce 中得到了这个。

代码如下:

let groupingsField = ['category'];
let aggregateField = ['price']

let [group, ...rest] = groupingsField
let [sum, ...noone] = aggregateField

const groupedData = data.reduce((acc, current) => {
  acc.push({
    [group]: current[group],
    [sum]: data.filter(item => item[group] === current[group])
    .map(el => el[sum])
    .reduce((total, current) => total + current)
  })

  return acc
}, [])
.reduce((acc, current) => {
  const x = acc.find(item => item[group] === current[group])

  return !x ? acc.concat([current]) : acc
}, [])

但是，我需要分组是动态的，如果那里存在超过 1 个值，它应该创建嵌套的 sub 数据集。应该可以添加多个分组。

//示例 2

grouping = ['category', 'currency'];
sum = ['price'];

//预期输出

[{
    category: 'Classic',
    price: 13,
    sub: [{
        currency: 'EUR',
        price: 7
    }, {
        currency: 'USD',
        price: 6
    }]
}, {
    category: 'Modern',
    price: 15,
    sub: [{
        currency: 'EUR',
        price: 9
    }, {
        currency: 'USD',
        price: 10
    }]
}]

因此，如果我要在分组中添加另一个键

grouping = ['category', 'currency', 'something'];

应该是三层深嵌套。

{
 category: 'Modern',
 price: 15,
 sub: [{
   currency: 'EUR',
   price: 9,
   sub: [{
     someting: ...
     price: ...
   }]
 }]
}

但是，我无法理解如何根据分组动态添加嵌套。我想我需要在这里进行一些递归。

希望得到一些帮助!

Answer 1

感谢您的帮助!然而，经过一段时间的 sleep 后，我想出了自己的解决方案:

groups = ['category', 'currency']; // this can be dynamic 
sum = ['price'];

function createGroup (groups, data, sum, childNode = 'sub') {
    let [primaryGroup, ...rest] = groups;

    let groupedData = data.reduce((acc, current) => {
    let chunk = {
        [primaryGroup]: current[primaryGroup],
        [sum]: data.filter(item => item[primaryGroup] === current[primaryGroup])
        .map(el => el[sum])
        .reduce((total, current) => total + current),
       ...(rest.length > 0 ? {[childNode]: createGroup(rest, data)} : {})
    }

    acc.push(chunk)
    return acc
  }, [])
    .reduce((acc, current) => {
        const x = acc.find(item => item[primaryGroup] === current[primaryGroup])
        return !x ? acc.concat([current]) : acc
    }, [])

  return groupedData;
}