Load ascx component using C# code

Question

Is there any way that I can use C# to load and then "render" an ascx control?

Essentially I am trying to replace inline ASP with a C# function which will return the same HTML. This would then let me set it as a webmethod so that I can update that section of the page with jQuery, using the same code that generated the original html.

I really need some way of doing this, and this seems like a logical route.

Answer 1

I've not tried this, but you can load a control using the LoadControl function:

Control Example = LoadControl("~\\Controls\\MyControl.ascx");

Then you could try rendering the control:

StringWriter sw = new StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
Example.RenderControl(htw);
Response.Write(sw.ToString());
Response.End();

But make sure that you override VerifyRenderingInServerForm and switch EnableEventValidation to false on the page.

Forget what I wrote above. I went back and tested and you can't call LoadControl because the webmethod is static. Since it's static you don't have a Page object to call... Which means no loading of user controls dynamically.

Answer 2

This Explanation should have the answers you are looking for. Basically you have to declare the control in the page then LoadControl in the codebehind.

Answer 3

You need to create a page in which you render the control:

public static string RenderUserControl(string path)
{
    Page pageHolder = new Page();
    Control viewControl = pageHolder.LoadControl(path);

    pageHolder.Controls.Add(viewControl);
    using(StringWriter output = new StringWriter())
    {
        HttpContext.Current.Server.Execute(pageHolder, output, false);
        return output.ToString();
    }
}

A user control on its own will not render. (This article has some related information from which I borrowed some code).

Answer 4

Keltex's answer was the only that worked for me since i was working with nested user-controls. Additionally, if you would want to pass parameters to your user control you can do so by:

_MyNameSpace_MyUserControl viewcontrol = (_MyNameSpace_MyUserControl) pageHolder.LoadControl(path);

viewcontrol.MyParam = "My value";