Question

I have UserControl that has asp control(<asp:Button runat=”server” ID=”btn” />) and I want to render it.

I tried 1:

            Page loader = new Page();

            Control ctrl = loader.LoadControl("WebUserControl1.ascx");
            loader.Controls.Add(ctrl);
            loader.ProcessRequest(context);

            StringBuilder sb = new StringBuilder();
            StringWriter sw = new StringWriter(sb);
            HtmlTextWriter htw = new HtmlTextWriter(sw);

            loader.RenderControl(htw);

It doesn’t works because it says that each control that has runat=”server” must be in Form.

I also tried 2:

Because loader.Form is null, I create HtmlForm and added the ctrl to it and then added HtmlForm to loader’s Control, BUT it says that it has 2 HtmlForm. So, instead I “injected” HtmlForm to loader like this

            Page loader = new Page();

            HtmlForm form = new HtmlForm();
            var method = loader.GetType().GetMethod("SetForm", BindingFlags.NonPublic | BindingFlags.Instance);
            method.Invoke(loader, new object[] { form });

            Control ctrl = loader.LoadControl("WebUserControl1.ascx");
            loader.Form.Controls.Add(ctrl);
            loader.ProcessRequest(context);

            StringBuilder sb = new StringBuilder();
            StringWriter sw = new StringWriter(sb);
            HtmlTextWriter htw = new HtmlTextWriter(sw);

            loader.RenderControl(htw);

Now no error is occurred, BUT StringWriter is empty

Where is my mistake.
Please don’t tell me to add Page to solution and override OnRender. I want to do it as I mentioned above.

Thank you

Answer 1

Dont use Form.Controls.Add,

Add a PlaceHolder control to Form. And add control to PlaceHolder.

PlaceHolder.Controls.Add(ctrl);

Try this.