Custom sorting by DisplayMember on ComboBox/Lookup column

HOW-TO
Implement custom sorting by DisplayMember instead of the default ValueMember

DESCRIPTION
Currently, RadGridView supports header click sorting that sorts data based on the cell values. This behavior is not suitable when you want to sort a ComboBox/Lookup column based on its displayed content instead their values.

SOLUTION
You could use custom sorting to change this default behavior. You only have to set CustomDataOperation property of your combo/lookup column to Sort and to subscribe for RadGridView's CustomSort event where you should implement your sort logic.

Here is some example code:
 
VB.NET


C#

private void Form1_Load(object sender, EventArgs e)

{

GridViewComboBoxColumn comboCol = new GridViewComboBoxColumn();

comboCol.DataSource = this.productsBindingSource; //this.nwindDataSet.Products;

comboCol.ValueMember = "ProductID";

comboCol.DisplayMember = "ProductName";

comboCol.FieldName = "ProductID";

comboCol.HeaderText = "Product Name";

comboCol.Width = 250;

this.radGridView1.Columns.Insert(2, comboCol);

comboCol.CustomDataOperation = CustomDataOperation.Sorting;

}

private void radGridView1_CustomSorting(object sender, GridViewCustomSortingEventArgs e)

{

//Find corespondent value

ComboBoxSorting.DataSources.NwindDataSet.ProductsRow tblRow1 =

this.nwindDataSet.Products.FindByProductID((int)e.CellValue1);

ComboBoxSorting.DataSources.NwindDataSet.ProductsRow tblRow2 =

this.nwindDataSet.Products.FindByProductID((int)e.CellValue2);

object value1 = String.Empty;

object value2 = String.Empty;

if (tblRow1 != null)

{

value1 = tblRow1["ProductName"];

}

if (tblRow2 != null)

{

value2 = tblRow2["ProductName"];

}

if (e.Column.SortOrder == RadSortOrder.Ascending)

{

e.SortResult = ((IComparable)value1).CompareTo(value2);

}

else

{

e.SortResult = ((IComparable)value1).CompareTo(value2) * (-1);

}

}