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"undefined" showing in empty DropDownList

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FormDecorator

This is a migrated thread and some comments may be shown as answers.

Jacopo asked on 28 Oct 2010, 11:43 AM

Hi,

after adding the RadFormDecorator to my project MasterPage, I've noticed this strange behavior: in every DropDownList that doesn't have any element, the word 'undefined' is displayed.

Here's a simple page that shows this behavior:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="DropDownList_undefined._Default" %>

<%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">

<title>Untitled Page</title>

</head>

<body>

<form action="Default.aspx" runat="server">

<telerik:RadScriptManager runat="server" id="sm1"></telerik:RadScriptManager>

<telerik:RadFormDecorator ID="RadFormDecorator1" runat="server" DecoratedControls="all" />

<asp:DropDownList runat="server" ID="ddlEmpty" Width="150px"></asp:DropDownList>

<asp:DropDownList runat="server" ID="ddlPopulated" Width="150px">

<asp:ListItem Text="Item1" Value="Item1"></asp:ListItem>

<asp:ListItem Text="Item2" Value="Item2"></asp:ListItem>

</asp:DropDownList>

</form>

</body>

</html>

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

namespace DropDownList_undefined

{

public partial class _Default : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

Is there any way to avoid this?

Thanks

3 Answers, 1 is accepted

answered on 01 Nov 2010, 03:52 PM

Hello Jacopo,

Could you please, explain your scenario in more detail and provide information why do you want to render an empty dropdownlist on the page?

According to the UX rules and recommendations it is not good to load empty dropdowns on the page. If you want to load items dynamically in the empty dropdown, than our suggestion is to load the dropdownlist control disabled:
<asp:DropDownList runat="server" ID="ddlEmpty" Width="150px" Enabled="false"></asp:DropDownList>

Once you add an item to the dropdown, just enable it.

Greetings,
Rumen
the Telerik team

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answered on 02 Nov 2010, 10:09 AM

Hi Rumen and thanks for your answer.
sometimes I need to load empty dropdowns in my pages. Just as an example think of a State/City selection scenario: at the PageLoad only the State dropdown is populated and after a user chooses the state, the City dropdown items are loaded.
Unfortunately we have tens of forms that behave this way in our application and it is really troublesome to have the 'undefined' word showing when the dropdowns are loaded. This is even more annoying since it seems that there is no way to localize or remove the text.

Besides, I've also tried to set the Enabled property to false like you suggested and, even if the dropdownlist is disabled and greyed out, the word 'undefined' is still there!

Maybe I can try to override this behavior if I know which script set the undefined word. Would it be possible for you to give me some suggestions about this?

Thanks for your help

&quot;undefined&quot; showing in empty DropDownList

3 Answers, 1 is accepted

"undefined" showing in empty DropDownList