我有,我想組和投硬型LINQ表達式List<DocumentGroup>
的LINQ表達的GroupBy
這LINQ查詢工作正常:
var DocumentGroups = (from dt in DocumentTypes
let dg = dt.DocumentGroup
select new DocumentGroup(){
Name = dg.Namn,
Id = dg.Id
}).GroupBy(group => group.Id).ToList();
現在我想要做同樣的查詢和投它以一個List<DocumentGroup>
但我收到此錯誤:
Unable to cast object of type 'Grouping[System.Guid,ConsoleApplication1+DocumentGroup]' to type 'DocumentGroup'.
List<DocumentGroup> DocumentGroups = (from dt in DocumentTypes
let dg = dt.DocumentGroup
select new DocumentGroup(){
Name = dg.Namn,
Id = dg.Id
}).GroupBy(group => group.Id).Cast<DocumentGroup>.ToList();
如果我雷莫ve .GroupBy(group => group.Id)
來自linq表達式,它工作正常,但我需要組表達式進行過濾。我該如何做這項工作?
的DocumentGroup類
public class DocumentGroup
{
public string Name { get; set; }
public Guid Id { get; set; }
}
如果您通過'ID'進行分組,則無法訪問聚合之外的'Name'。你想做什麼? – DavidG 2014-10-03 08:13:44