按多个对象分组数组 - JavaScript答案

【问题标题】：Group Array by multiple objects - JavaScript按多个对象分组数组 - JavaScript
【发布时间】：2021-09-07 10:40:58
【问题描述】：

我有一个数组，我必须按月份年份对值进行分组，然后键入并返回 leavecount 字段的总数，

如果数组项 holidayWork 有值，则创建一个新类型：WOH。

我的数组：

[
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-01-01T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Jan"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-02-03T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Jan"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-02-04T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Feb"
    },
    {
        "leavecount": 0.5,
        "holidayWork": 0,
        "dtAttendance": "2021-02-05T18:30:00.000Z",
        "vchLeaveTypeName": "Earned Leave",
        "vchLeaveTypeAlias": "EL",
        "Year": "2021",
        "mon": "Feb"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-03-06T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Mar"
    },
    {
        "leavecount": 0.5,
        "holidayWork": 0,
        "dtAttendance": "2021-04-07T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Apr"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-04-10T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Apr"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-04-11T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Apr"
    },
    {
        "leavecount": 0.5,
        "holidayWork": 0,
        "dtAttendance": "2021-05-12T18:30:00.000Z",
        "vchLeaveTypeName": "Casual/Sick Leave",
        "vchLeaveTypeAlias": "CL",
        "Year": "2021",
        "mon": "May"
    },
    {
        "leavecount": 1,
        "holidayWork": 1,
        "dtAttendance": "2021-05-12T18:30:00.000Z",
        "vchLeaveTypeName": "",
        "vchLeaveTypeAlias": "",
        "Year": "2021",
        "mon": "May"
    }
]

预期结果：

[
    {
        "Jan 2021" : [
            {
                "WFH" : 2
            }
        ],
        "Feb 2021" : [
            {
                "WFH" : 1
            },
            {
                "EL" : 0.5
            }
        ],
        "Mar 2021" : [
            {
                "WFH" : 1
            }
        ],
        "Apr 2021" : [
            {
                "WFH" : 2.5
            }
        ],
        "May 2021" : [
            {
                "WFH" : 0.5
            },
            {
                "WOH" : 0.5
            }
        ]
    }
]

我试过这段代码：

 let results = leaves.reduce(function (r, a) {
          r[a.mon+' '+a.vchYear] = r[a.mon+' '+a.vchYear] || [];
          r[a.vchYear][a.mon][a.vchLeaveTypeAlias].push(a)
          return r;
      }, Object.create(null));

请帮忙 .................................................. ..................................................... ..................................................... .....................

【问题讨论】：

我无法理解您的预期结果。为什么 May 2021 有 WFH 属性，而它应该有 CL 属性。还有为什么 2021 年 5 月 的 WOH 属性是 0.5

标签： javascript arrays sorting

【解决方案1】：

希望这是您所需要的（带有一些输出更正）：

const leaves = [
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-01-01T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Jan"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-02-03T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Jan"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-02-04T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Feb"
    },
    {
        "leavecount": 0.5,
        "holidayWork": 0,
        "dtAttendance": "2021-02-05T18:30:00.000Z",
        "vchLeaveTypeName": "Earned Leave",
        "vchLeaveTypeAlias": "EL",
        "Year": "2021",
        "mon": "Feb"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-03-06T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Mar"
    },
    {
        "leavecount": 0.5,
        "holidayWork": 0,
        "dtAttendance": "2021-04-07T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Apr"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-04-10T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Apr"
    },
    {
        "leavecount": 1,
        "holidayWork": 0,
        "dtAttendance": "2021-04-11T18:30:00.000Z",
        "vchLeaveTypeName": "Work From Home",
        "vchLeaveTypeAlias": "WFH",
        "Year": "2021",
        "mon": "Apr"
    },
    {
        "leavecount": 0.5,
        "holidayWork": 0,
        "dtAttendance": "2021-05-12T18:30:00.000Z",
        "vchLeaveTypeName": "Casual/Sick Leave",
        "vchLeaveTypeAlias": "CL",
        "Year": "2021",
        "mon": "May"
    },
    {
        "leavecount": 1,
        "holidayWork": 1,
        "dtAttendance": "2021-05-12T18:30:00.000Z",
        "vchLeaveTypeName": "",
        "vchLeaveTypeAlias": "",
        "Year": "2021",
        "mon": "May"
    }
];

let results = leaves.reduce(function (r, a) {
  const dateKey = `${a.mon} ${a.Year}`;
  r[dateKey] ??= [];

  let type;
  if (a.holidayWork !== 0) type = 'WOH';
  else type = a.vchLeaveTypeAlias;

  let typeEntry = r[dateKey].find(entry => entry[type] !== undefined);
  if (!typeEntry) {
    typeEntry = { [type]: 0 };
    r[dateKey].push(typeEntry);
  }

  typeEntry[type] += a.leavecount;
  return r;
}, Object.create(null));

console.log(results);

【讨论】：