在 JavaScript 中分組 - 平面數組到嵌套的 JSON

Question

我的前端打字稿文件中有這個列表：

月份：

0: {id: 1, companyName: "company14", companyId: 14, flActive: true, purchaseMonth: "2019-12-15T00:00:00", purchaseMonthString: "Dec-2019" , year: 2019, month: "December"}
1: {id: 2, companyName: "company5", companyId: 5, flActive: true, purchaseMonth: "2019-12-15T00:00:00", …}
2: {id: 3, companyName: "company13", companyId: 13, flActive: true, purchaseMonth: "2019-11-15T00:00:00", …}
3: {id: 4, companyName: "company14", companyId: 14, flActive: true, purchaseMonth: "2019-11-15T00:00:00", …}
4: {id: 5, companyName: "company5", companyId: 5, flActive: true, purchaseMonth: "2019-10-15T00:00:00", …}
5: {id: 6, companyName: "company14", companyId: 14, flActive: true, purchaseMonth: "2020-09-15T00:00:00", …}
6: {id: 7, companyName: "company7", companyId: 7, flActive: true, purchaseMonth: "2020-09-15T00:00:00", …}

我想從中獲取一個嵌套的樹 json，按 compnayName 和 year 屬性分組，類似於此但采用 JSON 格式：

我發現了這段代碼，但是它沒有完全返回結果，需要稍微調整一下：

keys = [
    'year',
    'companyName'
  ];

groupBy() {
    const drill = (o, key, ...keys) =>
      key ? drill((o[key] = o[key] || {}), ...keys) : o;
    const result = {};
    for (const e of this.poMonths) {
      const key = drill(
        result,
        e.companyName,
        e.year,

        e.month
      );
    }
    return result;
  }

我怎樣才能讓它工作？

Answer 1

您可以使用array.reduce()構建您的樹。 它以一個空對象開始，並在尚未在特定鍵下定義對象/數組時分配默認值（ ||運算符的右側將被執行）：

 let input = [{id: 1, companyName: "company14", companyId: 14, flActive: true, purchaseMonth: "2019-12-15T00:00:00", year: 2019, month: "December"}, {id: 2, companyName: "company5", companyId: 5, flActive: true, purchaseMonth: "2019-12-15T00:00:00", year: 2019, month: "December"}, {id: 3, companyName: "company13", companyId: 13, flActive: true, purchaseMonth: "2019-11-15T00:00:00", year: 2019, month: "November"}, {id: 4, companyName: "company14", companyId: 14, flActive: true, purchaseMonth: "2019-11-15T00:00:00", year: 2019, month: "December"}, {id: 5, companyName: "company5", companyId: 5, flActive: true, purchaseMonth: "2019-10-15T00:00:00", year: 2019, month: "October"}, {id: 6, companyName: "company14", companyId: 14, flActive: true, purchaseMonth: "2020-09-15T00:00:00", year: 2020, month: "September"}, {id: 7, companyName: "company7", companyId: 7, flActive: true, purchaseMonth: "2020-09-15T00:00:00", year: 2020, month: "September"}] let months = { "09": "September", "10": "October", "11": "November", "12": "December" } let result = input.reduce((state,current) => { let {companyName, year, month} = current; let company = state[companyName] || (state[companyName] = {}); let yearObj = company[year] || (company[year] = {}); let monthArr = yearObj[month] || (yearObj[month] = []); monthArr.push(current); return state; }, {}); console.log(result);