How to custom sort a string column so that all the empty cells in the WinForms GridGroupingControl?

2 mins read

Custom sorting

Description

By default, empty cells are included while sorting in the GridGroupingControl. To keep these empty cells always at the bottom while sorting, you have to implement an IComparer interface.

Solution

This customized sorting can be done by having a user-defined class that implements the IComparer interface and writing the custom comparer code in the Compare() method. Excluding the empty cells can be done by finding the length of the string in the Compare() method and cancelling its sorting, thereby pushing the empty cells to the bottom. Refer to the following code for implementing the Compare() method.

public class customsort : IComparer
{
    public int Compare(object x, object y)
    {
        if(x == null && y == null)
           return 0;
        // Does not include empty strings for comparison.
        else if (x == System.DBNull.Value)
        {
           return 0;
        }
        else if (y == System.DBNull.Value)
        {
           return 0;
        }
        else
        {
           return ((IComparable)x.ToString()).CompareTo(y.ToString());
        }
    }
}

Public Class customsort Implements IComparer
    Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer
        If x Is Nothing AndAlso y Is Nothing Then
           Return 0
        'Does not include empty strings for comparison.
        ElseIf x Is System.DBNull.Value Then
           Return 0
        ElseIf y Is System.DBNull.Value Then
           Return 0
        Else
           Return (CType(x.ToString(), IComparable)).CompareTo(y.ToString())
        End If
    End Function

You can create an instance of the SortColumnDescriptor for a particular column and set the Comparer() method to the instance of the inherited IComparer class. You can also initialize its sorting direction by using Sort Direction property.

//Sets the columnname to be sorted.
SortColumnDescriptor cd = new Syncfusion.Grouping.SortColumnDescriptor("City");
this.gridGroupingControl1.TableDescriptor.SortedColumns.Add(cd);
//Sets the sortdirection.
cd.SortDirection = System.ComponentModel.ListSortDirection.Descending;
//Handles the empty cells at the bottom.
cd.Comparer = new customsort();

'Sets the columnname to be sorted.
Dim cd As SortColumnDescriptor = New Syncfusion.Grouping.SortColumnDescriptor("City")
Me.gridGroupingControl1.TableDescriptor.SortedColumns.Add(cd)
'Sets the sortdirection.
cd.SortDirection = System.ComponentModel.ListSortDirection.Descending
'Handles the empty cells at the bottom.
cd.Comparer = New customsort()

Samples:

C#: Custom sorting

VB: Custom sorting

Reference link: https://help.syncfusion.com/windowsforms/gridgrouping/sorting#custom-sorting