c# - 来自 List 的数据拆分为另一个具有 2 个嵌套 List 的 List

Question

我在使用这个 linq 查询时遇到了一些麻烦:

我有一个列表 ( allStats ) 充满了数据(参见 allItems 类)该列表包含来自不同日期的多个条目，我需要对其进行分解，以便它们按月份和周数分开，如下所示:

    MonthNumber: 1,
    List<Weeks> Weeks:
        WeekNumber: 1,
        List<Days> Days:
            PunchedInLate: true,
            PunchedOutLate: false,
            PunchInDate: 2013-1-1 08:20:10,
            PunchOutDate: 2013-1-1 15:00:00
            PunchedInLate: true,
            PunchedOutLate: false,
            PunchInDate: 2013-1-2 08:20:10,
            PunchOutDate: 2013-1-2 15:00:00
            ...
            PunchedInLate: true,
            PunchedOutLate: false,
            PunchInDate: 2013-1-5 08:20:10,
            PunchOutDate: 2013-1-5 15:00:00
    MonthNumber: 1,
    List<Weeks> Weeks:
        WeekNumber: 2,
        List<Days> Days:
            PunchedInLate: true,
            PunchedOutLate: false,
            PunchInDate: 2013-1-10 08:20:10,
            PunchOutDate: 2013-1-10 15:00:00
            PunchedInLate: true,
            PunchedOutLate: false,
            PunchInDate: 2013-1-12 08:20:10,
            PunchOutDate: 2013-1-12 15:00:00

PasteBin - Here you can download a sample program so you can run it from your machine

它本质上是对我试图创建的这个问题的答案的补充: SO - Splitting parts of a List into 2 List's and joining those 2

EDIT: I am sorry, I forgot to mention that I've tried the .ToList() method at the end instead of the cast at the start which produces this error:

Cannot implicitly convert type 'System.Collections.Generic.List<System.Collections.Generic.IEnumerable<TestClass.Weeks>>' to 'System.Collections.Generic.List<TestClass.Weeks>'

public class allItems
{
    public DateTime PunchInDate { get; set; }
    public DateTime PunchOutDate { get; set; }
    public DayOfWeek DayOfWeek { get; set; }
    public int WeekNumber { get; set; }
    public int MonthNumber { get; set; }
    public bool PunchedInLate { get; set; }
    public bool PunchedOutLate { get; set; }
}
public class Months
{
    public int MonthNumber { get; set; }
    public List<Weeks> Weeks { get; set; }
}
public class Weeks
{
    public int WeekNumber { get; set; }
    public List<Days> Days { get; set; }
}
public class Days
{
    public bool PunchedInLate { get; set; }
    public bool PunchedOutLate { get; set; }
    public DateTime PunchInDate { get; set; }
    public DateTime PunchOutDate { get; set; }
    public DayOfWeek DayOfWeek { get; set; } 
}

还有代码:

List<allItems> allStats = getAllStats(userId);
List<Months> stats = new List<Months>();
var asItems =
    from item in allStats
    group item by new { month = item.MonthNumber } into Month
    select new Months()
    {
        MonthNumber = Month.Key.month,
        Weeks = Month.Select(week =>
            from weeks in allStats
            group weeks by new { week = weeks.WeekNumber } into Week
            select new Weeks()
            {
                //WeekNumber = week.WeekNumber,
                WeekNumber = Week.Key.week, // I just noticed that I guess that I 
                                            // need this here, so I can group the 
                Days = Month.Select(days => // days correctly, right?
                    new Days()
                    {
                        PunchedInLate = days.PunchedInLate,
                        PunchedOutLate = days.PunchedOutLate,
                        DayOfWeek = days.DayOfWeek,
                        PunchInDate = days.PunchInDate,
                        PunchOutDate = days.PunchOutDate
                    }).ToList()
            }).ToList()
    };
List<Months> stat = asItems.ToList();

Answer 1

问题是你的 Month.Select(...) 不返回 List<Weeks> .您可以删除类型转换并使用:

Week = Month.Select(week => 
    ... code as before ...
).ToList()

编辑:好的，我知道还有什么问题。对于每个 week ，您正在使用生成多个 Weeks 的查询对象。所以这部分:

from weeks in allStats
...
select new Weeks() { ... }

属于 IEnumerable<Weeks>() 类型- 这被用作 Month.Select(week => ...) 中的投影主体所以你有一系列的序列。目前尚不清楚您想如何将其变成一个列表。例如，您可以使用:

Week = Month.Select(week => 
    ... code as before ...
).First().ToList()

或:

Week = Month.Select(week => 
    ... code as before ...
).SelectMany(x => x).ToList()

我们对您要实现的目标的了解还不够。