c# - LINQ - Group List<T> 到年、月、日

Question

我有一个简单的列表

• T.Date = 11/04/2014, T.Title = "Book1", T.Tipology = "Book"
• T.Date = 14/04/2014, T.Title = "Book2", T.Tipology = "Book"
• T.Date = 02/05/2015, T.Title = "Spot1", T.Tipology = "Spot"
• T.Date = 21/06/2015, T.Title = "Newspaper1", T.Tipology = "Newspaper"

我需要按年、月、日对列表进行分组，如下所示:

• 2014
  • April
    • T.Date = 11/04/2014, T.Title = "Book1", T.Tipology = "Book"
    • T.Date = 14/04/2014, T.Title = "Book2", T.Tipology = "Book"
• 2015
  • May
    • T.Date = 02/05/2015, T.Title = "Spot1", T.Tipology = "Spot"
  • June
    • T.Date = 21/06/2016, T.Title = "Newspaper1", T.Tipology = "Newspaper"

所以我将能够在 foreach 函数中处理数据，例如:

 foreach(var year in Year)
 {
     foreach(var month in Month)
     {
         foreach(var day in Day)
         {
            Console.WriteLine(day.Item.Title);
            Console.WriteLine(day.Item.Tipology);
         }
         Console.WriteLine(month.ToString()); // With culture
     }
     Console.WriteLine(year.ToString());
 }

我如何使用 (c#) LINQ 做到这一点？

Answer 1

您可以按年、月、日排序:

var sorted = list.OrderBy(x=>x.Date.Year)
                 .ThenBy(x=>x.Date.Month)
                 .ThenBy(x=>x.Date.Day);

如果你真的想对它们进行分组，那么你可以这样做:

var result = from l in list
             group l by new { l.Date.Year,l.Date.Month} into g 
             select new
                   {
                     Year = g.Key.Year,
                     Month = g.Key.Month,
                     Items = g.ToList()
                    };

因此它将为您提供每年月份日期的分组数据