How to save exported excel at server directory

Question

I want to export data table in Excel sheet and saving in server directory in MVC application. Here is my code-

//ManagEmployeeController.cs

public JsonResult ExportToExcel()
        {
            Excel.ExcelUtlity obj = new Excel.ExcelUtlity();
            DataTable dt = ConvertToDataTable(ListEmployee());
            string dir = string.Format("~/Clients/ExportedData/");
            var directoryToSaveFile = Server.MapPath(dir);
            string uniqueNumber = DateTime.Now.ToString("yyyyMMddHHmmss");
            string file = "ContactExportData.xlsx";
            string newFileName = string.Format("{0}{1}", uniqueNumber, file);
            if (!Directory.Exists(directoryToSaveFile))
            {
                Directory.CreateDirectory(directoryToSaveFile);
            }
            string fullFilePath = string.Format("{0}/{1}",dir,newFileName); ;
            //obj.WriteDataTableToExcel(dt, "Person Details", "D:\\testPersonExceldata.xlsx", "Details");
            obj.WriteDataTableToExcel(dt, "Person Details", fullFilePath, "Details");
            var result = new { Success = "Success", Messaage = "SuccessMessage" };
            return Json(result,JsonRequestBehavior.AllowGet);
        }

The directory gets created but file does not saved here. But if I use commented code( obj.WriteDataTableToExcel(dt, "Person Details", "D:\\\\testPersonExceldata.xlsx", "Details"); ) the file gets saved on my local directory D.

//ExcelUtility.cs

 public bool WriteDataTableToExcel(System.Data.DataTable dataTable, string worksheetName, string saveAsLocation, string ReporType)
        {
 Microsoft.Office.Interop.Excel.Workbook excelworkBook;
    //
    //
    excelworkBook.SaveAs(saveAsLocation);;
       }

What is missing in my code in order to save Excel to mentioned directory on server?

Answer 1

string fullFilePath = string.Format("{0}/{1}",dir,newFileName);

应该：

string fullFilePath = string.Format("{0}/{1}",directoryToSaveFile,newFileName);