[英]Linq - get objects with a list property that does not contain values in another list
[英]LINQ: Get records in list with the largest values for property
我不知道它有多简单,
我有一个像这样的对象
public class ActionRecord
{
public int RecID { get; set; }
public string Action { get; set; }
public string ActArea { get; set; }
public int UserID { get; set; }
public DateTime ActDate { get; set; }
}
ActionRecord中的示例数据如下所示:
----------------------------------------------------------------------
RecID Action ActArea UserID ActDate
---------------------------------------------------------------------
1 Edit Main 1 Item 5 2014-11-01 10:01:14
2 Delete Sub 1 Item 2 2014-11-01 14:22:58
3 Add Sub 5 Item 2 2014-11-01 15:16:03
4 Add Sub 6 Item 2 2014-11-01 15:48:32
5 Edit Main 1 Item 2 2014-11-01 16:04:50
7 Edit Main 2 Item 5 2014-11-01 16:19:03
8 Delete Main 2 Item 5 2014-11-01 16:38:49
9 Add Main 3 Item 2 2014-11-01 16:42:25
10 Edit Main 3 Item 3 2014-11-01 16:45:38
我的要求是在LINQ的帮助下我需要过滤数据,这样我才能在ActArea上获得最新动作,这里的最终数据应该是这样的:
----------------------------------------------------------------------
RecID Action ActArea UserID ActDate
---------------------------------------------------------------------
10 Edit Main 3 Item 3 2014-11-01 16:45:38
8 Delete Main 2 Item 5 2014-11-01 16:38:49
5 Edit Main 1 Item 2 2014-11-01 16:04:50
4 Add Sub 6 Item 2 2014-11-01 15:48:32
3 Add Sub 5 Item 2 2014-11-01 15:16:03
2 Delete Sub 1 Item 2 2014-11-01 14:22:58
您可以使用GroupBy执行此操作:
var res = dara.GroupBy(d=>d.ActArea)
.Select(g=>g.OrderBydescending(a=>a.ActDate).First());
这就是我要做的:
var latest =
from x in all
group x by x.ActArea into gxs
from gx in gxs
.OrderByDescending(y => y.ActDate)
.Take(1)
select gx;
我得到的结果是:
这符合要求albiet,它不是相同的顺序。
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