protected override AccountInvoiceViewModel InitViewModelByDefault(AccountInvoiceViewModel simpleViewModel)
        {
            simpleViewModel = base.InitViewModelByDefault(simpleViewModel);

            if (simpleViewModel.VATInvoiceSeries == null)
            {
                simpleViewModel.VATInvoiceSeries = AccountInvoiceSession.GetVATInvoiceSeries(this.HttpContext);
            }

            return(simpleViewModel);
        }
 protected override void BackupViewModelToSession(AccountInvoiceViewModel simpleViewModel)
 {
     base.BackupViewModelToSession(simpleViewModel);
     AccountInvoiceSession.SetVATInvoiceSeries(this.HttpContext, simpleViewModel.VATInvoiceSeries);
 }