Question

我有一个这样的数组：

[{
   id: 1,
   amount: 10,
   date: '21/01/2017'
},{
   id: 1,
   amount: 10,
   date: '21/01/2017'
},{
   id: 1,
   amount: 30,
   date: '22/01/2017'
},{
   id: 2,
   amount: 10,
   date: '21/01/2017'
},]

我希望输出如下：

{
  '21/01/2017': {
    1: {
      amount: 20
    },
    2: {
      amount: 10
    }
  },
  '22/01/2017': {
    1: {
      amount: 30
    }
  }
}

基本上按数据分组，按id嵌套分组，同时汇总相关金额。

到目前为止，我已尝试使用reduce，并查看了lodash函数，但一直没有成功。 Reduce使得分组和求和很容易，但我找不到一种优雅的方法来创建第二级。我创建了一个沙箱来演示：

https://codesandbox.io/s/woj9xz6nq5

const dataToConsolidate = [{
  id: 1,
  amount: 10,
  date: '21/01/2017'
}, {
  id: 1,
  amount: 10,
  date: '21/01/2017'
}, {
  id: 1,
  amount: 30,
  date: '22/01/2017'
}, {
  id: 2,
  amount: 10,
  date: '21/01/2017'
},]

export const consolidate = (data) => {
  const result = data.reduce(function (res, obj) {

    (!(obj.date in res)) ?
      res.__array.push(res[obj.date] = obj) :
      res[obj.date].amount += obj.amount;

    return res;
  }, { __array: [] });

  return result;
};

console.log(consolidate(dataToConsolidate))

Answer 1

您可以将对象作为哈希表，并使用默认样式添加属性。

var array = [{ id: 1, amount: 10, date: '21/01/2017' }, { id: 1, amount: 10, date: '21/01/2017' }, { id: 1, amount: 30, date: '22/01/2017' }, { id: 2, amount: 10, date: '21/01/2017' }],
    result = {};

array.forEach(function (o) {
    result[o.date] = result[o.date] || {};
    result[o.date][o.id] = result[o.date][o.id] || { amount: 0 };
    result[o.date][o.id].amount += o.amount;
});

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

这是使用reduce的相对ES6-y解决方案：

＆＃13;

const initial = [{ id: 1, amount: 10, date: '21/01/2017' }, { id: 1, amount: 10, date: '21/01/2017' }, { id: 1, amount: 30, date: '22/01/2017' }, { id: 2, amount: 10, date: '21/01/2017' }];

const parse = obj => obj.reduce((final, { date, id, amount }) => {
  let group = final[date] = final[date] || {};
  group[id] = group[id] || { amount: 0 };
  group[id].amount += amount;
  return final;
}, {});

const final = parse(initial);
console.log(final);

＆＃13;

您希望添加适当的逻辑来处理丢失/错误的date，id或amount密钥。

Answer 3

作为图书馆的粉丝Ramda（免责声明：我是其中一位作者），我可能会用它来使一切更明确：

const {pipe, groupBy, prop, map, pluck, sum} = R

const data = [
  {"amount": 10, "date": "21/01/2017", "id": 1}, 
  {"amount": 10, "date": "21/01/2017", "id": 1}, 
  {"amount": 30, "date": "22/01/2017", "id": 1}, 
  {"amount": 10, "date": "21/01/2017", "id": 2}
]

const consolidate = pipe(
  groupBy(prop('date')),
  map(groupBy(prop('id'))),
  map(map(pluck('amount'))),
  map(map(sum))
)

console.log(consolidate(data))

.as-console-wrapper { max-height: 100% !important; top: 0; }

<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.25.0/ramda.min.js"></script>

当然，使用库来解决这个问题简直太过分了，比如来自@NinaSholz的解决方案就好了。但是如果你找到几个可以提供帮助的地方，可能值得研究一下这样的事情。

Answer 4

你可以通过_.groupBy：

来做到这一点

const res = _.chain(data)
    .groupBy('date')
    .mapValues(dateObj => _.chain(dateObj)
        .groupBy('id')
        .mapValues(idObj => ({ amount: _.sumBy(idObj, 'amount') }))
        .value()
     )
     .value();

ES6嵌套分组与总和

4 个答案: