public IActionResult Save(EditPurchaseVoucherVM model)
        {
            var voucher = _repo.GetByID(model.ID);

            voucher.VoucherCode              = model.VoucherCode;
            voucher.ExpirationDate           = model.ExpirationDate;
            voucher.Discount                 = model.Discount;
            voucher.NumberOfRedeemedVouchers = model.NumberOfRedeemedVouchers;
            _repo.Save();
            return(RedirectToAction("List"));
        }
        public IActionResult Edit(int ID)
        {
            var voucher = _repo.GetByID(ID);
            var model   = new EditPurchaseVoucherVM()
            {
                ID                       = voucher.ID,
                VoucherCode              = voucher.VoucherCode,
                Discount                 = voucher.Discount,
                ExpirationDate           = voucher.ExpirationDate,
                NumberOfRedeemedVouchers = voucher.NumberOfRedeemedVouchers
            };

            return(View(model));
        }