Export a GridView to Excel – C#
Posted by rameshch on July 10, 2008
when exporting excel in grid view am getting this error
System.Web.HttpException: Control ‘grdReport’ of type ‘GridView’ must be placed inside a form tag with runat=server. and
RegisterForEventValidation can only be called during Render();
The line: grdReport.RenderControl(htw); is tagged as the culprit. The original gridview is in a form tag with runat=server.
my solution as follows
<%@ Page Language="C#" AutoEventWireup="true" Codebehind="GridViewExport.aspx.cs" Inherits="ForForums.GridViewExport" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Untitled Page</title> </head> <body> <form id="form1" runat="server"> <div> <asp:GridView ID="CompanyListGridView" AutoGenerateColumns="false" CellPadding="3" CellSpacing="1" HeaderStyle-HorizontalAlign="Left" RowStyle-VerticalAlign="top" AlternatingRowStyle-VerticalAlign="top" RowStyle-BackColor="Lavender" AlternatingRowStyle-BackColor="LightBlue" HeaderStyle-BackColor="#006699" HeaderStyle-ForeColor="White" BorderStyle="None" BackColor="Black" GridLines="None" EmptyDataRowStyle-BackColor="Lavender" EmptyDataText="No records found." OnRowCreated="OnRowCreated" runat="server"> <Columns> <asp:BoundField DataField="CompanyName" ItemStyle-Width="300px" /> </Columns> </asp:GridView> <br /> <br /> <asp:Button ID="Button1" runat="server" Text="Export" OnClick="Button1_Click" /> </div> </form> </body> </html>
GridViewExport.aspx.cs:
using System; using System.Data; using System.Data.Common; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using Microsoft.Practices.EnterpriseLibrary.Data; namespace ForForums { public partial class GridViewExport : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { Database db = DatabaseFactory.CreateDatabase(); LoadCompanyList(db); } } protected void LoadCompanyList(Database db) { CompanyListGridView.DataSource = CompanyManager.GetCompanies(db); CompanyListGridView.DataBind(); } protected void OnRowCreated(object sender, GridViewRowEventArgs e) { if (e.Row.RowType == DataControlRowType.Header) foreach (TableCell headerCell in e.Row.Cells) headerCell.Text = "Company Name"; } protected void Button1_Click(object sender, EventArgs e) { GridViewExportUtil.Export("Companies.xls", this.CompanyListGridView); } } }
And a class file, GridViewExport.cs :
using System; using System.Data; using System.Configuration; using System.IO; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public class GridViewExportUtil { public static void Export(string fileName, GridView gv) { HttpContext.Current.Response.Clear(); HttpContext.Current.Response.AddHeader( "content-disposition", string.Format("attachment; filename={0}", fileName)); HttpContext.Current.Response.ContentType = "application/ms-excel"; using (StringWriter sw = new StringWriter()) { using (HtmlTextWriter htw = new HtmlTextWriter(sw)) { // Create a form to contain the grid Table table = new Table(); // add the header row to the table if (gv.HeaderRow != null) { GridViewExportUtil.PrepareControlForExport(gv.HeaderRow); table.Rows.Add(gv.HeaderRow); } // add each of the data rows to the table foreach (GridViewRow row in gv.Rows) { GridViewExportUtil.PrepareControlForExport(row); table.Rows.Add(row); } // add the footer row to the table if (gv.FooterRow != null) { GridViewExportUtil.PrepareControlForExport(gv.FooterRow); table.Rows.Add(gv.FooterRow); } // render the table into the htmlwriter table.RenderControl(htw); // render the htmlwriter into the response HttpContext.Current.Response.Write(sw.ToString()); HttpContext.Current.Response.End(); } } } /// <summary> /// Replace any of the contained controls with literals /// </summary> /// <param name="control"></param> private static void PrepareControlForExport(Control control) { for (int i = 0; i < control.Controls.Count; i++) { Control current = control.Controls[i]; if (current is LinkButton) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as LinkButton).Text)); } else if (current is ImageButton) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as ImageButton).AlternateText)); } else if (current is HyperLink) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as HyperLink).Text)); } else if (current is DropDownList) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as DropDownList).SelectedItem.Text)); } else if (current is CheckBox) { control.Controls.Remove(current); control.Controls.AddAt(i, new LiteralControl((current as CheckBox).Checked ? "True" : "False")); } if (current.HasControls()) { GridViewExportUtil.PrepareControlForExport(current); } } } }
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