dynamic sort columns doesn't work in linq - linq

Question

in linq i'm tring to create gridview with dynamic sort columns
can any one help me what is worng on below code and why it does't work
// i created this function to get column value which i need to sorty by
private static string GetReflectedPropertyValue( object subject, string field)
{
object reflectedValue = subject.GetType().GetProperty(field).GetValue(subject, null);
return reflectedValue != null ? reflectedValue.ToString() : "";
}
// this is my grid query
List<ticketSearchRes> tickets = new List<ticketSearchRes>();
// here i deteermined sort direction ascending or desc
bool asc = (gridViewInputsVM.SortDirection == "asc") ? true : false;
bool desc = (gridViewInputsVM.SortDirection != "asc") ? true : false;
IQueryable<ticketSearchRes> source = (from ticket in _db.TblTicket
where (searchRes.assignTic == 1) ? ticket.AssignedTo == CurrentuserId : true
where (searchRes.myTicket == 1 && searchRes.forOthers != 1) ? ticket.CreatedFor == CurrentuserId : true
orderby
asc ? GetReflectedPropertyValue(ticket, "TicketTitle") : "",
// here i need to get dynamic column which i need to sort by
desc ? GetReflectedPropertyValue(ticket, "TicketTitle") : "" descending // doesn't work
select new ticketSearchRes
{
title = (ticket.TicketTitle != null) ? ticket.TicketTitle.ToString() : "",
ticId = ticket.TicketId.ToString()
}).AsQueryable();

Answer 1

How I would solve this is;
The partial class TicketSearchResList is part that fills in the partial method CustomSort. CustomSort accepts a property name and a sort direction and uses Reflection to sort on the named property. So far it should be easy to follow.
public partial class TicketSearchResList : List<TicketSearchRes>
{
partial void CustomSort(string propertyName, string direction);
public void Dump()
{
CustomSort("TicketTitle", "desc");
foreach(var ticket in this)
Console.WriteLine(ticket.ToString()); // For demo purposes
}
}
public partial class TicketSearchResList {
private string propertyName;
private string direction;
partial void CustomSort(string propertyName, string direction)
{
this.propertyName = propertyName;
this.direction = direction;
Sort(Comparer);
}
private int Comparer(TicketSearchRes x, TicketSearchRes y)
{
int directionChanger = direction == "asc" ? 1 : -1;
try
{
PropertyInfo lhs = x.GetType().GetProperty(propertyName);
PropertyInfo rhs = y.GetType().GetProperty(propertyName);
object o1 = lhs.GetValue(x, null);
object o2 = rhs.GetValue(y, null);
if(o1 is IComparable && o2 is IComparable)
{
return ((IComparable)o1).CompareTo(o2) * directionChanger;
}
// No sort
return 0;
}
catch(Exception ex)
{
Debug.WriteLine(ex.Message); // Should log something
return 0;
}
}
The comparison is done using Reflection in the Comparer method. The direction is
used to determine whether to multiply the result by 1 or -1. CompareTo returns
an integer where -1 means less than, 0 means equal to, and 1 means greater than. Thus, if
you multiply the result by -1, you change the direction of the sort.
Finally, the TicketSearchResList class inherits from List<TicketResearchRes>. As you can see, the Dump method calls CustomSort, which, if implemented, yields ordered output.
Also, have a look at the Sort Method documented here by Microsoft