public IActionResult OnPost()
        {
            if (!ModelState.IsValid)
            {
                return(Page());
            }

            if (PaymentType.Id != Guid.Empty)
            {
                paymentTypeCommand.Update(PaymentType);
            }
            else
            {
                var result = paymentTypeCommand.Add(PaymentType.Description, PaymentType.LongDescription);

                if (result.IsFailure)
                {
                    TempData["Error"] = result.Error;
                    return(Page());
                }
            }

            return(RedirectToPage("./Detail", new { paymenttypeid = PaymentType.Id }));
        }