按数组分组

Question

我有一个 JSON 文件，我希望根据其中的三个字段对这个 JSON 进行分组。

JSON 如下所示（当然还有更多项目）：

{
  "Racename": "10KM",
  "Category": 34,
  "Gender": "Male",
  "Work": "Google",
  "FullName": "Dave Happner",
  "Rank": 1,
  "Ponit": 1,
  "Numparticipant": 0,
  "rankparticipant": 0,
  "precentagePart": "0",
  "NumRaces": 1,
  "RaceTime": "2018-10-18T00:34:20",
  "rankCat": 1,
  "PointCat": 1,
  "RaceDate": "2018-10-05"
}

请求的结果（使用underscore或lodash ）是：

 [ { "Racename" : "10KM", "Category": "34", "Gender": "Male", runner : [ { "Work": "Google", "FullName": "Dave Happner", "Rank": 1, "Ponit": 1, "Numparticipant": 0, "rankparticipant": 0, "precentagePart": "0", "NumRaces": 1, "RaceTime": "2018-10-18T00:34:20", "rankCat": 1, "PointCat": 1, "RaceDate": "2018-10-05" }]

Answer 1

您可以reduce为由字符串索引的对象，由Racename 、 Category和Gender ，并由不会出现在值中的字符（例如_ 。 例如，您在问题中的输入将生成一个键为10KM_34_Male的对象。 在每次迭代中，检查构造的键是否存在 - 如果不存在，则使用空的runner数组创建对象。 然后，推送到runner数组。

完成reduce ，您可以获取对象的值以获得所需的数组输出：

 const input = [{ "Racename": "10KM", "Category": 34, "Gender": "Male", "Work": "Google", "FullName": "Dave Happner", "Rank": 1, "Ponit": 1, "Numparticipant": 0, "rankparticipant": 0, "precentagePart": "0", "NumRaces": 1, "RaceTime": "2018-10-18T00:34:20", "rankCat": 1, "PointCat": 1, "RaceDate": "2018-10-05" }]; const outputObj = input.reduce((a, { Racename, Category, Gender, ...rest }) => { const key = [Racename, Category, Gender].join('_'); if (!a[key]) { a[key] = { Racename, Category, Gender, runner: [] }; } a[key].runner.push(rest); return a; }, {}); const output = Object.values(outputObj); console.log(output);

或者，使用更大的输入：

 const input = [{ "Racename": "10KM", "Category": 34, "Gender": "Male", "Work": "Google", "FullName": "Dave Happner", "Rank": 1, "Ponit": 1, "Numparticipant": 0, "rankparticipant": 0, "precentagePart": "0", "NumRaces": 1, "RaceTime": "2018-10-18T00:34:20", "rankCat": 1, "PointCat": 1, "RaceDate": "2018-10-05" },{ "Racename": "10KM", "Category": 34, "Gender": "Male", "Work": "Amazon", "FullName": "Bob Joe", "Rank": 12, "Ponit": 2, "Numparticipant": 0, "rankparticipant": 0, "precentagePart": "0", "NumRaces": 1, "RaceTime": "2018-10-18T00:34:20", "rankCat": 1, "PointCat": 1, "RaceDate": "2018-10-05" },{ "Racename": "20KM", "Category": 40, "Gender": "Male", "Work": "Google", "FullName": "Dave Happner", "Rank": 1, "Ponit": 1, "Numparticipant": 0, "rankparticipant": 0, "precentagePart": "0", "NumRaces": 1, "RaceTime": "2018-10-18T00:34:20", "rankCat": 1, "PointCat": 1, "RaceDate": "2018-10-05" } ]; const outputObj = input.reduce((a, { Racename, Category, Gender, ...rest }) => { const key = [Racename, Category, Gender].join('_'); if (!a[key]) { a[key] = { Racename, Category, Gender, runner: [] }; } a[key].runner.push(rest); return a; }, {}); const output = Object.values(outputObj); console.log(output);