Question

I’ve written a templated user control, MinimalTemplate, which currently does nothing other than render the HTML passed into its “ContentTemplate” placeholder. I want Visual Studio 2008 to have the same intellisense features for MinimalTemplate that it has for built-in templated controls such as Repeater.

Possibly related: I can manually type out my ContentTemplate tags, and it will build and run properly, but I get a validation error. I have already deleted the contents of my ReflectedSchemas folder, as suggested in this question.

Complete source for Minimal Template:

MinimalTemplate.ascx

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="MinimalTemplate.ascx.cs" Inherits="MyProject.MinimalTemplate" %>
<asp:placeholder runat=server id="contentPlaceHolder" />

MinimalTemplate.ascx.cs

using System.Web.UI;

namespace MyProject
{
    [ParseChildren(false)]
    public partial class MinimalTemplate : System.Web.UI.UserControl
    {

        [TemplateContainer(typeof(MessageContainer))]
        [TemplateInstance(TemplateInstance.Single)]
        public ITemplate ContentTemplate
        { get; set; }

        void Page_Init()
        {
            if (ContentTemplate != null)
            {
                MessageContainer container = new MessageContainer();
                ContentTemplate.InstantiateIn(container);
                contentPlaceHolder.Controls.Add(container);
            }
        }

        public class MessageContainer : Control, INamingContainer { }
    }
}

What changes can I make to my MinimalTemplate code so that Visual Studio will validate and autocomplete its ContentTemplate tag?

Answer 1

Related.

Add [PersistenceMode(PersistenceMode.InnerProperty)] to ContentTemplate’s attribute list. After adding it and rebuilding, the validation error disappeared and “ContentTemplate” appeared as expected in the Intellisense dropdown.

During my investigation, I’m certain I tried adding this property two or three times to no effect, so I expect the VS validator is a bit flaky. It smacks of voodoo programming, but do a Clean/Rebuild All and wait a few seconds before seeing whether the validation error persists.

(Also, you don’t need the ParseChildren attribute for this control.)