[Solved] Error with WebControl

[CYFL]

Hello,

I start with Telerik, and i woul'd like to put Telerik controls into webcontrol.
i have try many solution, but no one display me the result in the design mode.
I have an error : "Error Creating Control " "Object reference not set to an instance of an object."
but when I run the webpage, i see my Telerik control.

do you have an idea for this problems ?

my code :

Public Class Class11
    Inherits System.Web.UI.WebControls.WebControl

    Protected WithEvents RadComboBox2 As Global.Telerik.Web.UI.RadComboBox

 Public Sub New()
        MyBase.new()
        RadComboBox2 = New Telerik.Web.UI.RadComboBox
        RadComboBox2.ID = "toto"
    End Sub

Protected Overrides Sub Render(ByVal output As System.Web.UI.HtmlTextWriter)

        RadComboBox2.RenderControl(output)
        MyBase.CreateChildControls()
    End Sub

 Protected Overrides Sub CreateChildControls()
        Me.Controls.Clear()
        Me.Controls.Add(RadComboBox2)

    End Sub

thanks a lot !!!

[Daniel]

Hello,

Please examine the following blog post:
http://blogs.telerik.com/atanaskorchev/posts/09-03-06/Meet_Telerik_Web_Design_dll.aspx

Regards,
Daniel
the Telerik team

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[CYFL]

Hello

I try the propose solutions, but it does not work better,
I have always the error

: (

[CYFL]

nobody has never tested this mode?
:(

[Daniel]

Hello,

This error is caused due to the fact that RadComboBox is not yet added to the Controls collection of your custom control. RadComboBox is not aware that it is in design mode and it tries to render itself as it was on the page. To sidestep this problem, I recommend you call EnsureChildControls before calling the render method. Of course, this is not needed when your control is not in design mode.

public class MyControl : WebControl
{
    RadComboBox combo;
    public MyControl()
    {
        combo = new RadComboBox();
        combo.ID = "Test";
    }

    protected override void Render(System.Web.UI.HtmlTextWriter writer)
    {
        base.Render(writer);

        if (DesignMode)
        {
            EnsureChildControls();
            combo.RenderControl(writer);
        }
    }

    protected override void CreateChildControls()
    {
        Controls.Clear();
        Controls.Add(combo);
    }
}

Kind regards,
Daniel
the Telerik team

Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking system and vote to affect the priority of the items.