javascript - 使用 Lodash 对 Javascript 数组进行分组

Question

Transaction.ts

export class Transaction {
    id: string;
    category: Category = new Category();
    totalPrice: number;
}

类别.ts

export class Category {
    id: string;
    name: string;
}

我有一个 Transaction 数组，如下所示。

id:"1"
category: {id: "1", name: "Plumber"}
totalPrice: 500

id:"2"
category: {id: "1", name: "Plumber"}
totalPrice: 500

id:"3"
category: {id: "2", name: "Electrician"}
totalPrice: 1000

现在我需要对数据进行分组，如下所示。

我尝试使用lodash对其进行分组。但无法按照我需要的方式格式化(如上所示)。我可以在这里得到任何支持吗？

这是我尝试过的。它只是返回单个对象。之后呢？

let myArray = groupBy(this.data.transactions, (n) => {
      return n.category.name;
    });

像这样(这里的数据不同。只是虚拟数据)

更新:

 let a = groupBy(this.data.transactions, (n) => {
      return n.category.name;
    }).map((objs, key) => ({
      'name': key,
      'totalPrice': sumBy(objs, 'totalPrice')
    })).value();

上面给出了这个错误:

core.es5.js:1084 ERROR Error: Uncaught (in promise): TypeError: Object(...)(...).map is not a function TypeError: Object(...)(...).map is not a function

更新2:

  const resultArray = [...reduce(this.data.transactions,(r, { totalPrice, category: { name } }) => {
      const item = r.get(name) || {
        name,
        totalPrice: 0
      };

      item.totalPrice += totalPrice;

      return r.set(name, item);
    }, new Map()).values()];

错误:

ERROR Error: Uncaught (in promise): TypeError: Object(...)(...).values(...).slice is not a function TypeError: Object(...)(...).values(...).slice is not a function

Answer 1

您需要groupBy和sumBy，

var grouped =  _(jsonarray)
    .groupBy('category.name')
    .map((objs, key) => ({
        'name': key,
        'totalPrice': _.sumBy(objs, 'totalPrice') }))
    .value();

演示

var jsonarray = [{id:"1",
category: {id: "1", name: "Plumber"},
totalPrice: 500
},
{
id:"2",
category: {id: "1", name: "Plumber"},
totalPrice: 500
},
{
id:"3",
category: {id: "2", name: "Electrician"},
totalPrice: 1000
}];



var grouped =  _(jsonarray)
    .groupBy('category.name')
    .map((objs, key) => ({
        'name': key,
        'totalPrice': _.sumBy(objs, 'totalPrice') }))
    .value();

console.log(grouped);

<script src='https://cdn.jsdelivr.net/lodash/4.17.2/lodash.min.js'></script>