c# - 根据日期对列表进行分组，每个项目有多个日期

Question

我有一个如下列表:-

列表

编辑(生日和纪念日的年份可能不同)

- EmpGuid -265d317b-b819-4171-ba12-e64388746d81
Name - abc
Birthday - 15 Aug 2000
Anniversary- 12 july 1989

EmpGuid - 265d317b-b819-4171-ba12-e64388746d82
Name - xyz
Birthday - 24 Jan 2000
Anniversary- 15 Aug 1988

EmpGuid - 265d317b-b819-4171-ba12-e64388746d83
Name - mno
Birthday - 15 aug 2000
Anniversary- 24 Jan 1987

我想按照这样的日期对列表进行分组:-

12 July - abc anniversary

15 aug - abc Birthday
         mno Birthday
         xyz Anniversary

24 jan - xyz birthday
         mno anniversary

我试过这样做:-

 var groupedEmpList = FinalList.GroupBy(u => u.Birthdate)
                                      .Select(grp =>new { GroupID =grp.Key, FinalList = grp.ToList()})
                                      .ToList()

以上没有给我想要的输出。对此的任何帮助将不胜感激

Answer 1

此解决方案使用 SelectMany获取可以按项目分组的所有日期的扁平化列表:

var result = FinalList.Select(item => new 
                      { 
                          Date = new [] { item.Birthday.ToString("ddMM"), item.Anniversary.ToString("ddMM") }, 
                          Item = item 
                      })
                      .SelectMany(item => item.Date.Select(date => new { Date = date, Item = item.Item }))
                      .GroupBy(item => item.Date)
                      .Select(grouping => new { Date = grouping.Key, Events = grouping.ToList() }).ToList();

也可以执行第一个 select在 SelectMany 内- 为了回答的目的，我把它分开了

---

添加事件类型(并在删除第一个 select 的过程中):

var result = FinalList.SelectMany(item => new List<dynamic>
                        {
                            new { Date = item.Birthday.ToString("ddMM"), Event = "Birthday", Item = item },
                            new { Date = item.Anniversary.ToString("ddMM"), Event = "Anniversary", Item = item }
                        })
                      .GroupBy(item => item.Date)
                      .Select(grouping => new { Date = grouping.Key, Events = grouping.ToList() }).ToList();

---

要输出这些结果，您可以:

public enum EventTypes
{
    Birthday,
    Anniversary
}

public class Event
{
    public string Date { get; set; }
    public EventTypes Type { get; set; }
    public IEnumerable<dynamic> Items { get; set; }
}

var result = FinalList.SelectMany(item => new List<dynamic>
                        {
                            new { Date = item.Birthday.ToString("ddMM"), Type = EventTypes.Birthday, Item = item },
                            new { Date = item.Anniversary.ToString("ddMM"), Type = EventTypes.Anniversary, Item = item }
                        })
                      .GroupBy(item => new { item.Date, item.Type })
                      .Select(grouping => new Event { Date = grouping.Key.Date, Type = grouping.Key.Type, Items = grouping.ToList() }).ToList();

现在 result列表是 List<Event>在里面你也有你的 oridinal 对象在 Items (将该列表的 dynamic 替换为您原来的类类型 - 我只是不知道)