Add an "Export to Excel" button to a webpage to export gridview to excel in webapplication

i built a patient management software for a clinic and i need to export patiet list from ASP.net grid view to excel file

my question is:

Is there a way to export gridview to excel i am using vb.net and visual web developer 2010

i store datasource from advanced search page into a session and redirect to result pag开发者_C百科e here is the code of result page

Partial Class Sresults
Inherits System.Web.UI.Page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    GridView1.DataSource = Session("dsource")
    GridView1.DataBind()

End Sub

Protected Sub Backbtn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Backbtn.Click
    Session("dsource") = ""
    Response.Redirect("searchme.aspx")

End Sub

Protected Sub Page_PreRenderComplete(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRenderComplete
    Response.Write(GridView1.Rows.Count.ToString + " Records")
End Sub
End Class

try below code on the button click

// Get DataTable that DataGrid is bound to.
var dataTable = (DataTable)dataGrid.DataSource;

// Create new ExcelFile.
var ef = new ExcelFile();
// Add new worksheet to the file.
var ws = ef.Worksheets.Add(dataTable.TableName);
// Insert the data from DataTable to the worksheet starting at cell "A1".
ws.InsertDataTable(dataTable, "A1", true);

// Stream file to browser.
Response.Clear();
Response.ContentType = "application/vnd.ms-excel";
Response.AddHeader("Content-Disposition", "attachment; filename=Employee.xls");
ef.SaveXls(Response.OutputStream);
Response.End();

first you have to add the following to the page directive to avoid runtime error

 EnableEventValidation ="false"

add gridview to aspx page the session "dsource" is passing the datasource from advanced search page containing the connection string and select command then here is the code behind

using System;
using System.Data;
using System.Configuration;
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 System.Data.SqlClient;
using System.Threading;
using System.IO;
using System.Reflection;

public partial class csresults : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

    gridview1.DataSource = Session["dsource"];
    gridview1.DataBind();




}


  public override void VerifyRenderingInServerForm(Control control)
{

}



protected void Button2_Click(object sender, EventArgs e)
{
    HtmlForm form = new HtmlForm();
    string attachment = "attachment; filename=Patients.xls";
    Response.ClearContent();
    Response.AddHeader("content-disposition", attachment);
    Response.ContentType = "application/ms-excel";
    StringWriter stw = new StringWriter();
    HtmlTextWriter htextw = new HtmlTextWriter(stw);
    form.Controls.Add(gridview1);
    this.Controls.Add(form);
    form.RenderControl(htextw);
    Response.Write(stw.ToString());
    Response.End();
}

}