Linq and Group By Multiple Columns

It is typical master detail group by query.

We have data as List<T> which it contains master and detail columns (“SentData” in query).

Our master and detail classes:

public class Master { public string MasterID { get; set; } public string MasterDisplayValue{ get; set; } public List<Detail> Details { get; set; } } public class Detail { public string Detail1 { get; set; } public string Detail2 { get; set; } public string Detail3 { get; set; } }

We define columns for grouping with anonymous type;

var result = SentData.GroupBy(g=> new {OwnerID=g.AlbumOwner,OwnerDisplay=g.AlbumOwnerDisplayName }) .Select(resultgroup => new Master { MasterID = resultgroup.Key.OwnerID ,MasterDisplayValue = resultgroup.Key.OwnerDisplay ,Details = (resultgroup.Select(d => new Detail { Detail1 = d.Caption ,Detail2 = d.Description ,Detail3 = d.Count.ToString() }).ToList()) }).ToList();