RadControls for WinForms
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Custom sorting is a flexible mechanism for sorting RadGridView rows using custom logic. It has a higher priority than the applied SortDescriptors (added either by code or by clicking the header row).

Custom sorting is applied if user sorting is enabled by the RadGridView.EnableSorting or GridViewTemplate.EnableSorting properties. By default, sorting is enabled at all levels.

RadGridView provides two mechanisms for custom sorting:

  • Handling the CustomSorting event
  • Replacing the RadGridView sorting mechanism by providing a custom SortComparer

Using the CustomSorting event

The CustomSorting event is fired if custom sorting is enabled. The arguments of the event provide the following properties:

  • Template – the template that holds the rows which are going to be sorted
  • Row1, Row2 – the rows to be compared
  • SortResult – returns negative value when Row1 is before Row2, positive value if Row1 is after Row2 and zero if the rows are have equal values in a specified column.
  • Handled – defines if the comparison of the two rows is processed by the custom algorithm or by the applied sort descriptors.

The following example demonstrates how to handle the CustomSorting event sorting the RadGridView rows ascending by the values of the Freight column. The defined SortOrder for the Freight column in this example assumes that rows sorting is not applied. All RadGridView rows are processed by the custom logic.

Copy[C#]
this.radGridView1.EnableCustomSorting = true;
this.radGridView1.CustomSorting += new GridViewCustomSortingEventHandler(radGridView1_CustomSorting);

this.radGridView1.Columns["Freight"].SortOrder = RadSortOrder.Ascending;
Copy[C#]
private void radGridView1_CustomSorting(object sender, GridViewCustomSortingEventArgs e)
{
    decimal row1Freight = (decimal)e.Row1.Cells["Freight"].Value;
    decimal row2Freight = (decimal)e.Row2.Cells["Freight"].Value;
    if (row1Freight > row2Freight)
    {
        e.SortResult = 1;
    }
    else if (row1Freight < row2Freight)
    {
        e.SortResult = -1;
    }
    else
    {
        e.SortResult = 0;
    }
}
Copy[VB.NET]
Me.RadGridView1.EnableCustomSorting = True
Me.RadGridView1.Columns("Freight").SortOrder = RadSortOrder.Ascending
Copy[VB.NET]
Private Sub RadGridView1_CustomSorting(ByVal sender As Object, ByVal e As Telerik.WinControls.UI.GridViewCustomSortingEventArgs) Handles RadGridView1.CustomSorting
    Dim row1Freight As Decimal = CDec(e.Row1.Cells("Freight").Value)
    Dim row2Freight As Decimal = CDec(e.Row2.Cells("Freight").Value)

    If row1Freight > row2Freight Then
        e.SortResult = 1
    ElseIf row1Freight < row2Freight Then
        e.SortResult = -1
    Else
        e.SortResult = 0
    End If
End Sub
gridview-sorting-custom-sorting 001

The following example demonstrates the usage of the Handled property of the CustomSorting event arguments. It uses custom sorting to sort the rows ascending by the values of the Freight column. This sorting is applied to the rows that have a value in the Freight column greater than "0.33". The rest are handled by the defined SortDescriptor and sorted descending by the values of the Freight column.

Copy[C#]
this.radGridView1.EnableCustomSorting = true;
this.radGridView1.CustomSorting += new GridViewCustomSortingEventHandler(radGridView1_CustomSorting);

SortDescriptor sortDescriptor = new SortDescriptor("Freight", ListSortDirection.Descending);
this.radGridView1.SortDescriptors.Add(sortDescriptor);
Copy[C#]
private void radGridView1_CustomSorting(object sender, GridViewCustomSortingEventArgs e)
{
    decimal row1Freight = (decimal)e.Row1.Cells["Freight"].Value;
    decimal row2Freight = (decimal)e.Row2.Cells["Freight"].Value;

    if (row1Freight < 0.33m || row2Freight < 0.33m)
    {
        e.Handled = false;
        return;
    }

    if (row1Freight > row2Freight)
    {
        e.SortResult = 1;
    }
    else if (row1Freight < row2Freight)
    {
        e.SortResult = -1;
    }
    else
    {
        e.SortResult = 0;
    }
}
Copy[VB.NET]
Me.RadGridView1.EnableCustomSorting = True

Dim sortDescriptor As New SortDescriptor("Freight", ListSortDirection.Descending)
Me.RadGridView1.SortDescriptors.Add(sortDescriptor)
Copy[VB.NET]
Private Sub RadGridView1_CustomSorting(ByVal sender As Object, ByVal e As Telerik.WinControls.UI.GridViewCustomSortingEventArgs) Handles RadGridView1.CustomSorting
    Dim row1Freight As Decimal = CDec(e.Row1.Cells("Freight").Value)
    Dim row2Freight As Decimal = CDec(e.Row2.Cells("Freight").Value)

    If row1Freight < 0.33D OrElse row2Freight < 0.33D Then
        e.Handled = False
        Return
    End If

    If row1Freight > row2Freight Then
        e.SortResult = 1
    ElseIf row1Freight < row2Freight Then
        e.SortResult = -1
    Else
        e.SortResult = 0
    End If
End Sub

gridview-sorting-custom-sorting 002

Implementing sorting mechanism by using SortComparer

You can replace the sorting mechanism in RadGridView with a custom one by setting the SortComparer of the GridViewTemplate.

The following example demonstrates how to use a custom sorting mechanism in RadGridView to sort the RadGridView rows ascending by the length of the ShipCity column:

Copy[C#]
this.radGridView1.Columns["ShipCity"].SortOrder = RadSortOrder.Ascending;

this.radGridView1.MasterTemplate.SortComparer = new CustomComparer();
Copy[C#]
public class CustomComparer : IComparer<GridViewRowInfo>
{
    public int Compare(GridViewRowInfo x, GridViewRowInfo y)
    {
        int row1ShipCityLenght = x.Cells["ShipCity"].Value.ToString().Length;
        int row2ShipCityLenght = y.Cells["ShipCity"].Value.ToString().Length;

        int result = 0;
        if (row1ShipCityLenght > row2ShipCityLenght)
        {
            result = 1;
        }
        else if (row1ShipCityLenght < row2ShipCityLenght)
        {
            result = -1;
        }

        return result;
    }
}
Copy[VB.NET]
Me.RadGridView1.Columns("ShipCity").SortOrder = RadSortOrder.Ascending

Me.RadGridView1.MasterTemplate.SortComparer = New CustomComparer()
Copy[VB.NET]
Public Class CustomComparer
    Implements IComparer(Of GridViewRowInfo)

    Public Function Compare(ByVal x As GridViewRowInfo, ByVal y As GridViewRowInfo) As Integer Implements System.Collections.Generic.IComparer(Of Telerik.WinControls.UI.GridViewRowInfo).Compare
        Dim row1ShipCityLenght As Integer = x.Cells("ShipCity").Value.ToString().Length
        Dim row2ShipCityLenght As Integer = y.Cells("ShipCity").Value.ToString().Length

        Dim result As Integer = 0
        If row1ShipCityLenght > row2ShipCityLenght Then
            result = 1
        ElseIf row1ShipCityLenght < row2ShipCityLenght Then
            result = -1
        End If

        Return result
    End Function
End Class
gridview-sorting-custom-sorting 003