Hi all,

I need to add : <optgroup label ... in dropdownlist in code behind !

I don't find this property in dropdownlist!
How can i do ?
Thank you very much.

You can write your own Render method, or shortcut using something someone else has already created: http://www.codeplex.com/SharpPieces/

Direct property will not be there instead we need to do like this...

<asp:DropDownList ID="ddlItems" runat="server">
    </asp:DropDownList>

Imports System
Imports System.Collections
Imports System.Collections.Generic
Imports System.Configuration
Imports System.Data
Imports System.Linq
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI
Imports System.Web.UI.HtmlControls
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Xml.Linq
Imports System.Text
Imports System.IO
Imports System.Runtime.Serialization.Json
Imports System.Web.Script.Serialization
Public Partial Class Upload
    Inherits System.Web.UI.Page
    Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim item1 As New ListItem("Camel", "1")
        item1.Attributes("OptionGroup") = "Mammals"
       
        Dim item2 As New ListItem("Lion", "2")
        item2.Attributes("OptionGroup") = "Mammals"
       
        Dim item3 As New ListItem("Whale", "3")
        item3.Attributes("OptionGroup") = "Mammals"
       
        Dim item4 As New ListItem("Walrus", "4")
        item4.Attributes("OptionGroup") = "Mammals"
       
        Dim item5 As New ListItem("Velociraptor", "5")
        item5.Attributes("OptionGroup") = "Dinosaurs"
       
        Dim item6 As New ListItem("Allosaurus", "6")
        item6.Attributes("OptionGroup") = "Dinosaurs"
       
        Dim item7 As New ListItem("Triceratops", "7")
        item7.Attributes("OptionGroup") = "Dinosaurs"
       
        Dim item8 As New ListItem("Stegosaurus", "8")
        item8.Attributes("OptionGroup") = "Dinosaurs"
       
        Dim item9 As New ListItem("Tyrannosaurus", "9")
        item9.Attributes("OptionGroup") = "Dinosaurs"
       
        ddlItems.Items.Add(item1)
        ddlItems.Items.Add(item2)
        ddlItems.Items.Add(item3)
        ddlItems.Items.Add(item4)
        ddlItems.Items.Add(item5)
        ddlItems.Items.Add(item6)
        ddlItems.Items.Add(item7)
        ddlItems.Items.Add(item8)
        ddlItems.Items.Add(item9)
    End Sub
   
End Class
Public Class DropDownListAdapter
    Inherits System.Web.UI.WebControls.Adapters.WebControlAdapter
    Protected Overloads Overrides Sub RenderContents(ByVal writer As HtmlTextWriter)
        Dim list As DropDownList = TryCast(Me.Control, DropDownList)
       
        Dim currentOptionGroup As String
        Dim renderedOptionGroups As New List(Of String)()
       
        For Each item As ListItem In list.Items
            If item.Attributes("OptionGroup") Is Nothing Then
                RenderListItem(item, writer)
            Else
                currentOptionGroup = item.Attributes("OptionGroup")
               
                If renderedOptionGroups.Contains(currentOptionGroup) Then
                    RenderListItem(item, writer)
                Else
                    If renderedOptionGroups.Count &gt; 0 Then
                        RenderOptionGroupEndTag(writer)
                    End If
                   
                    RenderOptionGroupBeginTag(currentOptionGroup, writer)
                    renderedOptionGroups.Add(currentOptionGroup)
                   
                    RenderListItem(item, writer)
                End If
            End If
        Next
       
        If renderedOptionGroups.Count > 0 Then
            RenderOptionGroupEndTag(writer)
        End If
    End Sub
   
    Private Sub RenderOptionGroupBeginTag(ByVal name As String, ByVal writer As HtmlTextWriter)
        writer.WriteBeginTag("optgroup")
        writer.WriteAttribute("label", name)
        writer.Write(HtmlTextWriter.TagRightChar)
        writer.WriteLine()
    End Sub
   
    Private Sub RenderOptionGroupEndTag(ByVal writer As HtmlTextWriter)
        writer.WriteEndTag("optgroup")
        writer.WriteLine()
    End Sub
   
    Private Sub RenderListItem(ByVal item As ListItem, ByVal writer As HtmlTextWriter)
        writer.WriteBeginTag("option")
        writer.WriteAttribute("value", item.Value, True)
       
        If item.Selected Then
            writer.WriteAttribute("selected", "selected", False)
        End If
       
        For Each key As String In item.Attributes.Keys
            writer.WriteAttribute(key, item.Attributes(key))
        Next
       
        writer.Write(HtmlTextWriter.TagRightChar)
        HttpUtility.HtmlEncode(item.Text, writer)
        writer.WriteEndTag("option")
        writer.WriteLine()
    End Sub
End Class

Have a look at these too.

http://weblogs.asp.net/jeff/archive/2006/12/27/dropdownlist-with-optgroup.aspx

http://www.codeproject.com/KB/custom-controls/DropDownListOptionGroup.aspx