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Custom ServerControl inherited from RadListbox with requiredfieldvalidator not working

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This is a migrated thread and some comments may be shown as answers.
Vinayak
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Vinayak asked on 15 Sep 2011, 12:26 PM
Hi,

I am developing Custom server control(Ex : MyRadListBox) by inheriting from RadListBox. And I need RequiredFieldValidator inside the MyRadListBox class. Means need a RequiredFieldvalidator feature with My Custom server control. But its giving error like "Unable to find control id 'MyListBox1' referenced by the 'ControlToValidate' property of ''.

My Code is

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Telerik.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI;
 
namespace WebApplication1
{
    public class MyListBox : RadListBox
    {
        RequiredFieldValidator rfv ;
        protected override void CreateChildControls()
        {
            rfv = new RequiredFieldValidator();
            rfv.ControlToValidate = this.ID;
            rfv.ErrorMessage = "This is required";
            rfv.EnableClientScript = true;
            base.Controls.Add(rfv);
            base.CreateChildControls();
        }
 
        protected override void Render(HtmlTextWriter writer)
        {
            base.Render(writer);
            rfv.RenderControl(writer);
        }
    }
}

But If I inherit from simple ASP Listbox it works fine. Look at below code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Telerik.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI;
 
namespace WebApplication1
{
    public class MyListBox : ListBox
    {
        RequiredFieldValidator rfv ;
        protected override void CreateChildControls()
        {
            rfv = new RequiredFieldValidator();
            rfv.ControlToValidate = this.ID;
            rfv.ErrorMessage = "This is required";
            rfv.EnableClientScript = true;
            base.Controls.Add(rfv);
            base.CreateChildControls();
        }
 
        protected override void Render(HtmlTextWriter writer)
        {
            base.Render(writer);
            rfv.RenderControl(writer);
        }
    }
}

I am not getting why its not working with RadListBox and why its working with normal asp ListBox control?

Please kindly help me to resolve this problem.

Thanks
Vinayak


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