C# Webforms User controls in VB.NET

Question

I have an existing VB.NET web project that requires some new screens (webforms). Due to a number of reasons these new screens are to be developed in C#. Having had a read around it appears that this is indeed possible: Adding C# Web Form to VB Web Application and add c# user control to existing asp.net vb.net project

However I have done a small test of:

VB.NET Solution containing a VB WebForms application project
Added a new C# ASP.NET Project to the solution
Created web user control in C# assembly
Referenced and used web user control in a Default.aspx in 1.

Problem is the user control does not display on the page. What have I missed here. Is this something that is not possible in a VB.NET WebForms app? Below is the relevant code:

Default.aspx

<%@ Page Title="Home Page" Language="VB" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Default.aspx.vb" Inherits="waWithCUserControl._Default" %>
<%@ Register TagPrefix="uac" Namespace="waUserControls" Assembly="waUserControls" %>

<asp:Content runat="server" ID="BodyContent" ContentPlaceHolderID="MainContent">
    <uac:UcTakeTest ID="myUserControl" runat="server" />
</asp:Content>

User Control In Seperate Assembly waUserControls

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="ucTakeTest.ascx.cs" Inherits="waUserControls.UcTakeTest" %>
<link href="//netdna.bootstrapcdn.com/bootstrap/3.0.3/css/bootstrap.min.css" rel="stylesheet">
<script src="//netdna.bootstrapcdn.com/bootstrap/3.0.3/js/bootstrap.min.js"></script>
<link href="//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.min.css" rel="stylesheet">

    <div class="container">
        <div class="row">
            <div class="col-md-2">
                <div class="list-group">
                    <a href="#" class="list-group-item active">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                    <a href="#" class="list-group-item">Question</a>
                </div>
            </div>
         </div>
    </div>

There is lot of discussion about this.. stackoverflow.com/questions/1977220/… — Anand Thangappan
– Anand Thangappan, Commented Dec 13, 2013 at 4:59
That relates to an asp WEBSITE whereas I am interested in an asp APPLICATION (webforms). While I realise it is possible to have CS code in App_Code folder that does not appear to be a solution when there are designer files and ascx files involved. Unless I am wrong about that? — TheEdge
– TheEdge, Commented Dec 13, 2013 at 5:06

sh1rts · Accepted Answer · 2013-12-23 04:01:52Z

4

You need to postbuild the markup (ASCX files only) from the C# project into your VB Web Application project, and reference those ASCX's instead of the C# ones. Sounds bizarre but believe me it works.

1 - Add a post-build event to the C# project that copies the UserControl markup (just the .ASCX files) to a folder in your Web Application project; for example, a folder under the root of your web app called "ExternalUserControls"

(Note that they should have the same Inherits property, i.e. the namespace and classname from the C# project.)

2 - Make sure the C# project is referenced (sounds like it already is)

3 - Add control declarations to the <controls> section of <pages> of <system.web> in web.config: -

  <system.web>
  .
  .
  <pages>
    <controls>
      <add tagPrefix="cc" 
           src="~/ExternalUserControls/MyControl.ascx" 
           tagName="MyControl"   />
      <add .... etc

4 - reference the controls in your page thusly: -

<cc:MyControl id="testControl" runat="server" ..

5 - make sure you Import the correct namespace for the control as defined in the C# project

6 - Note that sometimes the VS Page Designer will refuse to add a variable for your control, so in order to access your control in the code-behind you will need to add a page-level protected (or whatever VB's equivalent is, I can't remember) variable of the correct type, using the same name as in the page markup (testControl in the example above)

Let me know if you want an example.

edited Dec 23, 2013 at 4:01

answered Dec 13, 2013 at 6:26

sh1rts

1,8841 gold badge13 silver badges14 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

TheEdge Over a year ago

You are a scholar and a gentleman sir. That worked perfectly. Much appreciated.

sh1rts Over a year ago

You're welcome. You should have seen the look on my face when someone told me (a long time ago) this was the solution.. But it works !

Andy Over a year ago

For anyone keeping score, this same approach also works for including VB.NET controls inside C# web forms.

Collectives™ on Stack Overflow

C# Webforms User controls in VB.NET

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related