Can’t access public properties of registered User Controls inside a Sharepoint 2010 Visual Web Part

Problem

I was trying to use a user control within a Sharepoint 2010 Visual Web Part and can’t seem to access any of the public properties of the user controls.

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Casting the user control explicitly seem to do the trick. But I don’t want to do that every time!

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What’s really happening

When I created the dependant user control that the visual web part require, VS2010 automatically create a special Sharepoint’s Control Template folder for me – which is kinda neat.

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Worth pointing out that the User control has a ‘deployment location’ property where it says to which folder it’s going to be deployed to.

In the Visual Webpart, I’ve registered the user control as such.

<%@ Register Tagprefix="UserControl" TagName="NotificationList" Src="~/_ControlTemplates/WebParts/NotificationList.ascx" %>

Note that the source is _ControlTemplates rather than ControlTemplates. If I had omitted the underscore it wouldn’t work as there isn’t such folder in Sharepoint. I worked this out by looking at the path which the generated Visual Web Part bootstrapper point to .

If you look closer, Visual Studio 2010 doesn’t seem to like our user control registration.

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It’s suggesting that it can’t find the control and decided to put the base class System.Web.UI.UserControl in our Visual Web Part designer class (*.ascx.design.cs). This is the culprit of why we can’t get the public properties/methods without explicit cast.

Seems the problem is caused by Visual Studio 2010 not having the same assumptions with the Sharepoint 2010 runtime. It’s really a VS2010 Bug.

VS2010 should’ve generated \_ControlTemplates\ in the first place when I create user controls. Alternatively, VS2010 should simply accept that ControlTemplates is a merely string token that will be converted to _ControlTemplates by Sharepoint 2010 runtime and take this account when generating the designer classes.

Solution

The solution is very simple:

  1. Register the user control as above – i.e point src to ~/_ControlTemplates/ …
  2. Simply rename the ControlTemplate solution folder in VS2010 to _ControlTemplate

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As soon as I did this, VS2010 T4 template (which generates the designer classes) behaves properly and casts my user controls to the proper types.

  • Markus J

    I just figured this out… right before I stumbled upon your post! Arghhh… Over a year later and there isn't a patch/fix for this in VS2010?

    Thanks for sharing though… keep up the good work dude.