RadControls for ASP.NET AJAX
By default, RadComboBox sorts items by their Text property. This article will show you how to implement custom sorting - the items will be sorted by their Value property.
For this purpose, we will use the IComparer interface which exposes a method that compares two objects.
Here are the two steps that you need to perform:
1. Create a class that implements IComparer for your custom sorting:
CopyC#
public class SortComboItemsByValue : IComparer
{
public int Compare(object x, object y)
{
RadComboBoxItem p1 = new RadComboBoxItem();
RadComboBoxItem p2 = new RadComboBoxItem();
if (x is RadComboBoxItem)
p1 = x as RadComboBoxItem;
else
throw new ArgumentException("Object is not of type RadComboBoxItem.");
if (y is RadComboBoxItem)
p2 = y as RadComboBoxItem;
else
throw new ArgumentException("Object is not of type RadComboBoxItem.");
int cmp = 0;
if (p1.ComboBoxParent.Sort == RadComboBoxSort.Ascending)
{
cmp = String.Compare(p1.Value, p2.Value, !p1.ComboBoxParent.SortCaseSensitive);
}
if (p1.ComboBoxParent.Sort == RadComboBoxSort.Descending)
{
cmp = String.Compare(p1.Value, p2.Value, !p1.ComboBoxParent.SortCaseSensitive) * -1;
}
return cmp;
}
}CopyVB.NET
Public Class SortComboItemsByValue
Implements IComparer
Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer
Dim p1 As New RadComboBoxItem()
Dim p2 As New RadComboBoxItem()
If TypeOf x Is RadComboBoxItem Then
p1 = TryCast(x, RadComboBoxItem)
Else
Throw New ArgumentException("Object is not of type RadComboBoxItem.")
End If
If TypeOf y Is RadComboBoxItem Then
p2 = TryCast(y, RadComboBoxItem)
Else
Throw New ArgumentException("Object is not of type RadComboBoxItem.")
End If
Dim cmp As Integer = 0
If p1.ComboBoxParent.Sort = RadComboBoxSort.Ascending Then
cmp = [String].Compare(p1.Value, p2.Value, Not p1.ComboBoxParent.SortCaseSensitive)
End If
If p1.ComboBoxParent.Sort = RadComboBoxSort.Descending Then
cmp = [String].Compare(p1.Value, p2.Value, Not p1.ComboBoxParent.SortCaseSensitive) * -1
End If
Return cmp
End Function
End Class
2. Call the overloaded SortItems or Items.Sort methods passing your IComparer as a parameter:
CopyC#
RadComboBox2.Sort = RadComboBoxSort.Ascending;
RadComboBox2.SortItems(new SortComboItemsByValue());
CopyVB.NET
RadComboBox2.Sort = RadComboBoxSort.Ascending
RadComboBox2.SortItems(New SortComboItemsByValue())
That's it. Now the combobox items will be sorted by their Values instead of Text.
See Also