C#

Object reference not set to an instance of an object.

protected void DocumentUpload_OnFileUploadComplete(object sender, FileUploadCompleteEventArgs e)
      {
          if (!e.UploadedFile.IsValid) return;

          GridViewDetailRowTemplateContainer container = ((Control)sender).NamingContainer as GridViewDetailRowTemplateContainer;
          Int32 index = container.VisibleIndex;

          var orderId = Convert.ToInt32(ViewOrdersGridView.GetRowValues(index, ViewOrdersGridView.KeyFieldName));
          var fileNumber = ViewOrdersGridView.GetRowValues(index, ElsaConstants.FileNumber).ToString();
          var userId = Convert.ToInt32(Session[ElsaConstants.UserId]);
          string directory = ConfigurationManager.AppSettings[ElsaConstants.UploadDirectory];
          if (!Directory.Exists(directory))
          {
              Directory.CreateDirectory(directory);
          }

          string fileType = Path.GetExtension(e.UploadedFile.FileName);
          string fileName = e.UploadedFile.FileName.Replace(fileType, string.Format("_{0}{1}", fileNumber, fileType));
          string resultFilePath = directory + fileName;
          e.UploadedFile.SaveAs(resultFilePath, true);//MapPath

          using (var context = new ELSAEntities())
          {
              var document = new Document
              {
                  OrderId = orderId,
                  DocumentPath = fileName,
                  DateCreated = DateTime.Now,
                  CreatedBy = userId
              };

              context.Document.Add(document);
              context.SaveChanges();
          }
      }

<list>
<person>
<name>Micky Mouse</name>
<phone>
<phone1>1111111</phone1>
<phone2>2222222</phone2>
</phone>
</person>
<person>
<name>Donald Duck</name>
<phone>
<phone1>3333333</phone1>
</phone>
</person>
<person>
<name>Pluto</name>
<phone>
</phone>
</person>
<person>
<name>Goofy</name>
<phone>
<phone1>5555555</phone1>
<phone2>6666666</phone2>
<phone3>7777777</phone3>
</phone>
</person>
.....
.....
.....
</list>