public ActionResult Edit(EditViewModel editViewModel)
        {
            if (editViewModel == null)
            {
                throw new HttpException(400, "Bad Request");
            }

            var voucherTemplate = VoucherTemplateService.FindById(editViewModel.VoucherTemplateId);
            if (voucherTemplate == null)
            {
                throw new HttpException(404, "Not Found");
            }

            voucherTemplate.Name = editViewModel.Name;
            voucherTemplate.Description = editViewModel.Description;
            var oldTemplateFile = voucherTemplate.TemplateFile;

            foreach (string file in Request.Files)
            {
                if (Request.Files[file].ContentLength <= 0 || Request.Files[file] == null)
                    continue;
                string pathToSave = Server.MapPath("~/Files/VoucherTemplates");
                string fileExtension = Path.GetExtension(Request.Files[file].FileName);
                string uploadFileName = String.Format(Guid.NewGuid() + fileExtension);
                Request.Files[file].SaveAs(Path.Combine(pathToSave, uploadFileName));
                voucherTemplate.TemplateFile = Path.Combine(pathToSave, uploadFileName);
            }

            if (oldTemplateFile != voucherTemplate.TemplateFile)
            {
                if (System.IO.File.Exists(oldTemplateFile))
                {
                    System.IO.File.Delete(oldTemplateFile);
                }
            }
            VoucherTemplateService.UpdateVoucherTemplate(voucherTemplate);      
            TempData["VoucherTemplateId"] = voucherTemplate.VoucherTemplateId;
            TempData["VoucherTemplateName"] = voucherTemplate.Name;
            TempData["Message"] = DocumentsMessage.EditSuccess;
            return RedirectToAction("index", "vouchertemplates");
        }
        public ActionResult Edit(int? id)
        {
            if (id == null)
            {
                throw new HttpException(400, "Bad Request");
            }

            var voucherTemplate = VoucherTemplateService.FindById(id.Value);
            if (voucherTemplate == null)
            {
                throw new HttpException(404, "Not Found");
            }

            var editViewModel = new EditViewModel()
            {
                VoucherTemplateId = voucherTemplate.VoucherTemplateId,
                Name = voucherTemplate.Name,
                Description = voucherTemplate.Description,
                TemplateFile = voucherTemplate.TemplateFile,
            };
            return View(editViewModel);
        }