c# - GridView must be placed inside a form tag with runat="server" even after the GridView is within a form tag

Question

<form runat="server" id="f1">
    <div runat="server" id="d">
        grid view:
        <asp:GridView runat="server" ID="g">
        </asp:GridView>
    </div>

    <asp:TextBox runat="server" ID="t" TextMode="MultiLine" Rows="20" Columns="50"></asp:TextBox>
</form>

Code behind:

public partial class ScriptTest : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        g.DataSource = new string[] { "a", "b", "c" };
        g.DataBind();

        TextWriter tw = new StringWriter();
        HtmlTextWriter h = new HtmlTextWriter(tw);    
        d.RenderControl(h);
        t.Text = tw.ToString();
    }
}

Even the GridView is within a from tag with runat="server", still I am getting this error.

Any clues please ?

Answer 1

You are calling GridView.RenderControl(htmlTextWriter), hence the page raises an exception that a Server-Control was rendered outside of a Form.

You could avoid this execption by overriding VerifyRenderingInServerForm

public override void VerifyRenderingInServerForm(Control control)
{
  /* Confirms that an HtmlForm control is rendered for the specified ASP.NET
     server control at run time. */
}

See here and here.