UserControl 的 RenderControl 要求(C# .NET)中的表单标记

问题描述

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();

解决方案

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 */}
    }
}

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