Question

The base class includes the field ‘lbl’, but its type (web.App_Code.CustomLabelControl) is not compatible with the type of control (web.App_Code.CustomLabelControl).

I had done many custom controls before the same way but today I ran into this error.

I have a web application project with the below class in App_Code directory a tagprefix reference in web.config for the control in class.

What do I do now?

Web.Config

<system.web>
    <pages>
        <controls>
            <add namespace="web.App_Code" tagPrefix="CControls"/>...

Markup

<form id="form1" runat="server">
<div>
    <CControls:CustomLabelControl runat="server" OnClickText="Welcome" ID="lbl">
    </CControls:CustomLabelControl>
</div>
</form>

Class File

namespace web.App_Code
{
    public class CustomLabelControl : Control, IPostBackEventHandler, IPostBackDataHandler
    {
        private string _onClickText;

        public CustomLabelControl()
        {

        }

        public string OnClickText
        {
            get { return _onClickText; }
            set { _onClickText = value; }
        }

        public void RaisePostBackEvent(string eventArgument)
        {
            throw new System.NotImplementedException();
        }


        public bool LoadPostData(string postDataKey, NameValueCollection postCollection)
        {
            throw new System.NotImplementedException();
        }


        public void RaisePostDataChangedEvent()
        {
            throw new System.NotImplementedException();
        }
    }
}

I’ve checked these resources already:

• The base class includes the field 'btnLogin', but its type (FoodOrder.App_Code.LinkButtonDefault) is not compatible

• http://support.microsoft.com/kb/919284

• Base class includes the field 'X', but its type (System.Web.UI.ScriptManager) is not compatible with the type of control (System.Web.UI.ScriptManager)

Answer 1

Try specifying the assembly name too:

<add tagPrefix="CControls" namespace="web.App_Code" assembly="web.App_Code" />

I would consider creating a dedicated namespace for your custom controls, just for the sake of clarity. Maybe something like web.App_Code.CustomControls:

<add tagPrefix="CControls" namespace="web.App_Code.CustomControls" assembly="web.App_Code.CustomControls" />