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Dynamically loaded RadComboBox using JavaScript

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Ajax

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

Eric Schuler asked on 18 Feb 2011, 12:48 AM

Hi,

I have trouble to set selected value for a RadComboBox using Javascript.

I think the trouble I have is because the RadComboBox is loaded dynamically in a user control.

Actually the whole website is built based on multiple user controls with AJAX, which mean, there is no post back.

I tried:

function JSSelect() {

var combo = $find("<%= RadComboBox1.ClientID %>");

var itm = combo.findItemByValue('04');

itm.select();

}

I want to call this function at a proper time when the user control which contain my RadComboBox is loaded. But I think it's because of "<%=" and "%>", the page will try to find RadComboBox1 first when the page is first request, but at this time, the user control which contains my RadComboBox has not been loaded. How can I solve this problem?

12 Answers, 1 is accepted

answered on 01 Feb 2012, 01:20 AM

Hi Telerik,

I facing a similar issue but different way and I tried the solution which you proposed but it is not working.
I am doing a migration from VS 2005(RAD 2003) to 2010 (RAD 2010 Q3 ASP.NET Ajax) - so I can not change the componets in my old code except the modification which is reqired to work RAD 2010 .
here the issue is Radcombobox is not loading properly when it calls. it is always showing null , I have used
ScriptManager.RegisterStartupScript as per your suggestion but it didn't work, I have created a sample project both in 2010 (with RAD 2010) & 2005 (with RAD 2003). it is working perfectly in 2005 but not in 2010- can you please help on this,
I have attached both projects along with this post
code which is working in 2005
default.aspx

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

<%@ Register Assembly="RadComboBox.Net2" Namespace="Telerik.WebControls" TagPrefix="radC" %>

<! 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" >

<title>Untitled Page</title>

</head>

<body>

<div>

<table>

<tr>

</span>

<radC:RadComboBox

ID="rcbDateRangePicker" runat="server" OnClientBlur="ChangeDate" Height="190px" Width="110px"> </radC:RadComboBox>

</td> <td><asp:Image ID="imgBtn" runat="server" /> </td>

</tr>
</table>

</div>

</form>

</body>

</html>

default.aspx.cs

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;

using Telerik.WebControls;

using System.Text;

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

{

protected void Page_Load(object sender, EventArgs e)

{

RadDatePicker startDateControl = new RadDatePicker();

RadDatePicker endDateControl = new RadDatePicker();

if (!IsPostBack)

{

imgBtn.Attributes.Add("onclick", "TogglePicker();");

DateTime now = DateTime.Now;

DateTime lastMonth = DateTime.Now.AddMonths(-1);

rcbDateRangePicker.Items.Add(new RadComboBoxItem("None"));

AddDate(now, now, "Today");

AddDate(now.AddDays(-30), now, "Last 30 Days");

AddDate(now.AddDays(-45), now, "Last 45 Days");

//set default

(startDateControl as RadDatePicker).DbSelectedDate = DateTime.Now;

(endDateControl as RadDatePicker).DbSelectedDate = DateTime.Now;

}

StringBuilder builder = new StringBuilder();

builder.AppendLine(

"<script type=\"text/javascript\">");

builder.AppendLine("var combo = null;");

builder.AppendLine("try { combo = " + rcbDateRangePicker.ClientID + " } catch(err){}");

builder.AppendLine(@"function TogglePicker()

{

if(combo==null)

{

alert('this object is empty');

var itemSelected = combo.SelectedItem.Value;

alert(itemSelected)

}

else

{

alert('this object is not empty');

var itemSelected = combo.SelectedItem.Value;

alert(itemSelected)

}

function ChangeDate()

{

if(combo==null)

{

alert('this object is empty');

var itemSelected = combo.SelectedItem.Value;

}

else

{

alert('this object is not empty');

}

);

builder.AppendLine(

"</script>");

if (!Page.ClientScript.IsClientScriptBlockRegistered("DateRangeScript"))

Page.ClientScript.RegisterStartupScript(

this.GetType(), "DateRangeScript", builder.ToString());

}

private void AddDate(DateTime startDate, DateTime endDate, string text)

{

RadComboBoxItem item = new RadComboBoxItem(text, text);

item.Attributes.Add("StartDate", startDate.ToString());

item.Attributes.Add("EndDate", endDate.ToString());

if (text.Equals("Today") && !Page.IsPostBack)

item.Selected = true;

rcbDateRangePicker.Items.Add(item);

}

================================================================================

code which is not working with 2010
default.aspx

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"

CodeFile="Default.aspx.cs" Inherits="_Default" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">

</asp:Content>

<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">

<table>

<tr>

<telerik:RadScriptManager ID="radSctMgr" runat ="server">

</telerik:RadScriptManager>

</span>

<telerik:RadComboBox ID="rcbDateRangePicker" runat="server" OnClientBlur="ChangeDate" Height="190px"

Width="110px">

</telerik:RadComboBox>

</td>

</tr>

</table>

</asp:Content>

default.aspx.cs

using System;
using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Text;
using Telerik.Web.UI;

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

{

string someScript = string.Empty;

protected void Page_Load(object sender, EventArgs e)

{

RadDatePicker startDateControl = new RadDatePicker();

RadDatePicker endDateControl = new RadDatePicker();

if (!IsPostBack)

{

imgBtn.Attributes.Add("onclick", "TogglePicker();");

DateTime now = DateTime.Now;

DateTime lastMonth = DateTime.Now.AddMonths(-1);

rcbDateRangePicker.Items.Add(new RadComboBoxItem("None"));

AddDate(now, now, "Today");

AddDate(now.AddDays(-30), now, "Last 30 Days");

AddDate(now.AddDays(-45), now, "Last 45 Days");

//set default

(startDateControl as RadDatePicker).DbSelectedDate = DateTime.Now;

(endDateControl as RadDatePicker).DbSelectedDate = DateTime.Now;

}

StringBuilder builder = new StringBuilder();

builder.AppendLine("<script type=\"text/javascript\">");

builder.AppendLine("var comboCal = null;");

builder.AppendLine("var comboCal = $find('" + rcbDateRangePicker.ClientID + "');");

// builder.AppendLine("try { comboCal = $find(\"<%=" + rcbDateRangePicker.ClientID + " %>\") } catch(err){}");

//builder.AppendLine("try { comboCal = " + rcbDateRangePicker.ClientID + " } catch(err){}");

builder.AppendLine(@"function TogglePicker()

{

if(comboCal==null)

{

alert('this object is empty');

var itemSelected = comboCal.SelectedValue;

alert(itemSelected);

}

else

{

alert('this object is not empty');

var itemSelected = comboCal.SelectedValue;

alert(itemSelected);

}

function ChangeDate()

{

if(comboCal==null)

{

alert('this object is empty');

var itemSelected = comboCal.SelectedValue;

}

else

{

alert('this object is not empty');

}

");

builder.AppendLine("</script>");

//someScript = "Sys.Application.add_load(" + builder.ToString() + ");";

//ScriptManager.RegisterStartupScript(Page, this.GetType(), "onload", someScript, true);

if (!Page.ClientScript.IsClientScriptBlockRegistered("DateRangeScript"))

Page.ClientScript.RegisterStartupScript( this.GetType(), "DateRangeScript", builder.ToString());

}
private void AddDate(DateTime startDate, DateTime endDate, string text)

{

RadComboBoxItem item = new RadComboBoxItem(text, text);

item.Attributes.Add("StartDate", startDate.ToString());

item.Attributes.Add("EndDate", endDate.ToString());

if (text.Equals("Today") && !Page.IsPostBack)

item.Selected = true;

rcbDateRangePicker.Items.Add(item);

}

answered on 01 Feb 2012, 06:29 PM

Hello,

When RadComboBox is placed inside a UserControl its client ID is changed. You could use the following method to find the control:

var comboJQueryObject = $telerik.$("[id$='_RadComboBox1']");

var combo = $find(comboJQueryObject.attr["id"]);

if(combo){

combo.findItemByValue("04").select();

}

As for registering a client script from the server, attached is a sample page showing how to do it. You could download it and give it a try locally.

I hope this is helpful.

All the best,
Ivana
the Telerik team

If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed now

answered on 04 Feb 2012, 01:30 AM

Thanks Ivana.
sorry for delayed reply since I was out of town.
I have tried the solution which you have attached and I am able to get the value if the function is calling from the control combobox ( using sender.get_text()) but here the issue is I am calling the Java script function from some other control ( say Button) and that function required combobox object to be modified.
e.g from the attached file Test.aspx.cs (I have tried with $Telerik and even with direct controlID taken from view source)
I have modified few lines

string

handlerClientItemsRequested = "function OnClientLoad(sender, args){ \n"

//var comboCal= $find(""<%= RadComboBoxCategory.ClientID %>"");

" var comboCal = $find('" + RadComboBoxCategory.ClientID + "'); \n"

+ " if(comboCal==null) { alert('this object is empty'); } else {alert('this object is not empty');} \n"

+ " alert(comboCal.SelectedValue);" //not working

+ " alert(sender.get_text()); \n" //this is working

+ " \n"

+ "}";
in this case comboCal is always Null ( just consider this function is calling from some other control or combobox itself - both ways it is not working)
I have created a proj even with out user control but in vein. I am using Master pages.
Everything is fine with old version -- I have both proj created and is there any way to send the sample project to you- attachment of zip is not allowing here.
Thanks in Advance

answered on 07 Feb 2012, 06:05 PM

Thx Ivava,
I am Pasting the code below - when I click on the button on the below project then the combobox control is getting Null- but it is working in 2005 - so please let me know whether I missed anything here or should I use another method. ASPX (Default.aspx) - used ScriptManager as well as Client Script to register.

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
CodeFile="Default.aspx.cs" Inherits="_Default" %>
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<table>
<tr>
<telerik:RadScriptManager ID="radSctMgr" runat ="server">
</telerik:RadScriptManager>
<td><span id="comboHolder">
</span>
<telerik:RadComboBox ID="rcbDateRangePicker" runat="server" OnClientBlur="ChangeDate"Height="190px"Width="110px">
</telerik:RadComboBox></td><td><asp:Image ID="imgBtn" runat="server" /> </td></tr>
</table></asp:Content>

default.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Text;
using Telerik.Web.UI;
public partial class _Default : System.Web.UI.Page
{
string someScript = string.Empty;
protected void Page_Load(object sender, EventArgs e)
{RadDatePicker startDateControl = new RadDatePicker();
RadDatePicker endDateControl = new RadDatePicker();
if (!IsPostBack)
{imgBtn.Attributes.Add("onclick", "TogglePicker();");
DateTime now = DateTime.Now;
DateTime lastMonth = DateTime.Now.AddMonths(-1);
rcbDateRangePicker.Items.Add(new RadComboBoxItem("None"));
AddDate(now, now, "Today");
AddDate(now.AddDays(-30), now, "Last 30 Days");
AddDate(now.AddDays(-45), now, "Last 45 Days");
//set default
(startDateControl as RadDatePicker).DbSelectedDate = DateTime.Now;
(endDateControl as RadDatePicker).DbSelectedDate = DateTime.Now;
}

StringBuilder builder = new StringBuilder();
builder.AppendLine("<script type=\"text/javascript\">");
builder.AppendLine("var comboCal = null;");
builder.AppendLine("var comboCal = $find('" + rcbDateRangePicker.ClientID + "');");
// builder.AppendLine("try { comboCal = $find(\"<%=" + rcbDateRangePicker.ClientID + " %>\") } catch(err){}");
//builder.AppendLine("try { comboCal = " + rcbDateRangePicker.ClientID + " } catch(err){}");
builder.AppendLine(@"function TogglePicker()
{
if(comboCal==null)
{
     alert('this object is empty');
     var itemSelected = comboCal.SelectedValue;
     alert(itemSelected);
}
else
{
    alert('this object is not empty');
    var itemSelected = comboCal.SelectedValue;
    alert(itemSelected);
}

}

private void AddDate(DateTime startDate, DateTime endDate, string text)
{
RadComboBoxItem item = new RadComboBoxItem(text, text);
item.Attributes.Add("StartDate", startDate.ToString());
item.Attributes.Add("EndDate", endDate.ToString());
if (text.Equals("Today") && !Page.IsPostBack) item.Selected = true;
rcbDateRangePicker.Items.Add(item);
}
}

--------------
Master(site.master.cs)
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head runat="server">
<title></title>
<link href="~/Styles/Site.css" rel="stylesheet" type="text/css" />
<asp:ContentPlaceHolder ID="HeadContent" runat="server">
</asp:ContentPlaceHolder>
</head>
<body><form runat="server"><div class="page"><div class="header"><div class="title">
<h1>My ASP.NET Application</h1></div></div><div class="main"><asp:ContentPlaceHolder ID="MainContent" runat="server"/></div><div class="clear"></div></div>
<div class="footer">
</div>
</form>
</body></html>

---Config Files

<?xml version="1.0"?>

<!--

For more information on how to configure your ASP.NET application, please visit

http://go.microsoft.com/fwlink/?LinkId=169433

-->

<system.web>

</controls>

</pages>

</httpHandlers>

</system.web> <system.webServer><modules runAllManagedModulesForAllRequests="true"/>

</system.webServer>

</configuration>

answered on 09 Feb 2012, 04:59 PM

Hi ,
I can provide you a very simple example. in this below example I am getting "combo " null can u please check what I missed from this.
if I use the Java script in aspx or if I call the function from RadComboBox event then I am able to get but I need to get the the object of RadComboBox from this structure - please help me to find out -Thx in advance.
Structure
-----------
1:controls in aspx
2:Java script in aspx.cs ( registering from Page Load) - Javascript Register control is Page
3:calling the Java script function from other control ( not from RadCombobox) for getting the object of RadComboBox.

Default.aspx
<%@ Page Title="Home Page" Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

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

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

<head id="Head1" runat="server">

<title></title> <link href="~/Styles/Site.css" rel="stylesheet" type="text/css" />

</head>

<body>

<form runat="server" id="test">
<telerik:RadScriptManager ID="RadScriptManager1" runat ="server">
</telerik:RadScriptManager>

<table><tr><td><telerik:RadComboBox ID="rcbDateRangePicker" runat="server" Height="190px" Width="110px"> </telerik:RadComboBox></td>

<td><asp:Image ID="imgBtn" runat="server" /> </td></tr>

</table> </form> </body> </html>

Default.aspx.cs
==================

using System;

using System.Web.UI;

using System.Text;

using Telerik.Web.UI;

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

{

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

{

imgBtn.Attributes.Add("onclick", "TogglePicker();");

DateTime now = DateTime.Now;

DateTime lastMonth = DateTime.Now.AddMonths(-1);

rcbDateRangePicker.Items.Add(new RadComboBoxItem("None"));

rcbDateRangePicker.Items.Add(new RadComboBoxItem("Today"));

}

StringBuilder builder = new StringBuilder();

builder.AppendLine(@"function TogglePicker()

{

alert('inside Toggle');

var combo = $find(""<%= rcbDateRangePicker.ClientID %>"");

alert(combo.get_text());}");

ScriptManager.RegisterStartupScript(Page, this.GetType(), "onloadOfDocument", builder.ToString(), true);

}