public ActionResult Create(CreateInvoice formModel)
        {
            InvoiceRepo repo = new InvoiceRepo(context);

            try
            {
                var invoice = new Invoice(formModel.InvoiceNumber, formModel.Status, formModel.ClientId);
                invoice.Status = InvoiceStatus.Open;
                repo.Insert(invoice);
                return(RedirectToAction("Index"));
            }
            catch (DbUpdateException ex)
            {
                HandleDbUpdateException(ex);
            }

            formModel.PopulateSelectLists(context);
            return(View("Create", formModel));
        }