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c#html.netuser-controls

UserControl's RenderControl is asking for a form tag in (C# .NET)


I asked how to render a UserControl's HTML and got the code working for a dynamically generated UserControl.

Now I'm trying to use LoadControl to load a previously generated Control and spit out its HTML, but it's giving me this:

Control of type 'TextBox' must be placed inside a form tag with runat=server.

I'm not actually adding the control to the page, I'm simply trying to grab its HTML. Any ideas?

Here's some code I'm playing with:

TextWriter myTextWriter = new StringWriter();
HtmlTextWriter myWriter = new HtmlTextWriter(myTextWriter);

UserControl myControl = (UserControl)LoadControl("newUserControl.ascx");
myControl.RenderControl(myWriter);

return myTextWriter.ToString();

Solution

  • Alternatively you could disable the ServerForm/Event-validation on the page that is rendering the control to a string.

    The following example illustrates how to do this.

    public partial class _Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string rawHtml = RenderUserControlToString();
        }
    
        private string RenderUserControlToString()
        {
            UserControl myControl = (UserControl)LoadControl("WebUserControl1.ascx");
    
            using (TextWriter myTextWriter = new StringWriter())
            using (HtmlTextWriter myWriter = new HtmlTextWriter(myTextWriter))
            {
                myControl.RenderControl(myWriter);
    
                return myTextWriter.ToString();
            }
        }
    
        public override void VerifyRenderingInServerForm(Control control)
        { /* Do nothing */ }
    
        public override bool EnableEventValidation
        {
            get { return false; }
            set { /* Do nothing */}
        }
    }