Sorting RadDropDownList Numerically by Value

Environment

Product	RadDropDownList for ASP.NET AJAX
Version	All

Description

I want to sort the items of a RadDropDownList numerically based on their Value property instead of the Text property. By default, the control sorts items by Text. Is there a way to sort the RadDropDownList by numeric values programmatically?

This knowledge base article also answers the following questions:

• How can I sort RadDropDownList items by value in ASP.NET AJAX?
• Is it possible to perform numeric sorting on RadDropDownList?
• How to sort RadDropDownList using code-behind?

Solution

To sort the RadDropDownList items numerically by their Value, you can perform custom sorting in the code-behind. The following example demonstrates how to achieve this:

Code Example

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        // Define RadDropDownList items
        List<DropDownListItem> tourItems = new List<DropDownListItem>
        {
            new DropDownListItem("Alps Tour", "100"),
            new DropDownListItem("Desert Safari", "25"),
            new DropDownListItem("Island Escape", "7"),
            new DropDownListItem("Mountain Hike", "50"),
            new DropDownListItem("City Lights", "300")
        };

        // Sort by Value numerically
        List<DropDownListItem> sortedItems = tourItems.OrderBy(item => int.Parse(item.Value)).ToList();

        // Clear existing items and add sorted items
        RadDropDownList1.Items.Clear();
        foreach (DropDownListItem item in sortedItems)
        {
            RadDropDownList1.Items.Add(item);
        }
    }
}

Explanation

1. Sorting Items: The code uses LINQ to sort the items based on their numeric Value. The int.Parse method is used to ensure the sorting is numerical rather than alphabetical.
2. Re-adding Items: After sorting, the existing items are cleared using RadDropDownList1.Items.Clear(). The sorted items are then added back to the control.

Notes

• Ensure that all Value properties can be parsed into integers. If the values are non-integer, adjust the parsing logic accordingly.
• This approach is ideal when you need to customize sorting behavior for RadDropDownList items.

See Also

• RadDropDownList Overview
• RadComboBox vs RadDropDownList
• Sorting Items in RadComboBox