<form id="form1" runat="server">
        <asp:GridView ID="assCorsiGrid" BorderStyle="Solid" BorderColor="#ff9900" BorderWidth="1" runat="server" DataSourceID="ObjectDataSource1" AllowPaging="True" AllowSorting="True" CellPadding="4" ForeColor="#333333" GridLines="None">
            <FooterStyle BackColor="#990000" Font-Bold="True" ForeColor="White" />
            <RowStyle BackColor="#ffe7c6" ForeColor="#333333" />
            <SelectedRowStyle BackColor="#FFCC66" Font-Bold="True" ForeColor="Navy" />
            <PagerStyle BackColor="#FFCC66" ForeColor="#333333" HorizontalAlign="Center" />
            <HeaderStyle BackColor="#ff9900" Font-Bold="True" ForeColor="#ffffff" />
            <AlternatingRowStyle BackColor="White" />
        </asp:GridView>
        <asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="ReportAssistenzaCorsi"
        TypeName="GestioneCompetenze.BL.ManageReport"></asp:ObjectDataSource>
    
        <asp:Button runat="server" ID="stampa" Text="stampa" OnClick="stampa_Click" />
    </form>

    protected void stampa_Click(object sender, EventArgs e)
    {
        StringWriter stringWriter = new StringWriter();
        HtmlTextWriter html = new HtmlTextWriter(stringWriter);
        assCorsiGrid.RenderControl(html);
    }

        StringWriter stringWriter = new StringWriter();
        HtmlTextWriter html = new HtmlTextWriter(stringWriter);
        HtmlForm form = new HtmlForm();
        Page.Controls.Add(form);
        form.Controls.Add(assCorsiGrid);
        form.RenderControl(html);