How to Export Dynamically created Data Gridviews into Excel using open xml...

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using GridToExcel.Data;
using GridToExcel.Helper;
using System.IO;

namespace AMC_Main.Reports
{
    public partial class GridXml : System.Web.UI.Page
    {
        DataGrid grdvTest = new DataGrid();
        protected void Page_Load(object sender, EventArgs e)
        {
 
          
        }
        //private void gridBind()
        //{
            
        //}

        protected void btnExport_Click(object sender, EventArgs e)
        {
            DataTable table = new DataTable();
            AMC.Business.StudioMain objStudio = new StudioMain();
            DataTable dtsearch = new DataTable();
            dtsearch = objStudio.SearchStudioTemp();
            if (dtsearch.Rows.Count > 0)
            {
                // pnlStudioInfo.Visible = true;
                grdvTest.DataSource = dtsearch;
                ViewState["file"] = dtsearch;
                grdvTest.DataBind();
            }


            

            string file = new ExcelHelper().ExportToExcel(dtsearch);
          //  string file1 = new ExcelHelper().ExportToExcel(dtsearch);
            string rootPath = HttpContext.Current.Server.MapPath("~").ToString();
            string localCopy = Guid.NewGuid().ToString() + ".xlsx";
          //  string localCopy1 = Guid.NewGuid().ToString() + ".xlsx";
            File.Copy(file, rootPath + localCopy);
           // File.Copy(file1, rootPath + localCopy1);
            Response.Redirect(localCopy);

        }
       
    }
}

internal string ExportToExcel(DataTable table)
        {
            string excelfile = Path.GetTempPath() + Guid.NewGuid().ToString() + ".xlsx";
            using (SpreadsheetDocument excelDoc = SpreadsheetDocument.Create(excelfile, DocumentFormat.OpenXml.SpreadsheetDocumentType.Workbook))
            {
                CreateExcelParts(excelDoc, table);
            }
            return excelfile;
        }

        private void CreateExcelParts(SpreadsheetDocument spreadsheetDoc, DataTable data)
        {
            WorkbookPart workbookPart = spreadsheetDoc.AddWorkbookPart();
            CreateWorkbookPart(workbookPart);

            int workBookPartCount = 1;

            WorkbookStylesPart workbookStylesPart = workbookPart.AddNewPart<WorkbookStylesPart>("rId" + (workBookPartCount++).ToString());
            CreateWorkbookStylesPart(workbookStylesPart);

            WorksheetPart worksheetPart = workbookPart.AddNewPart<WorksheetPart>("rId" + (101).ToString());
            CreateWorksheetPart(workbookPart.WorksheetParts.ElementAt(0), data);

            SharedStringTablePart sharedStringTablePart = workbookPart.AddNewPart<SharedStringTablePart>("rId" + (workBookPartCount++).ToString());
            CreateSharedStringTablePart(sharedStringTablePart, data);

            workbookPart.Workbook.Save();
        }