public DeliveryOrder VHasNoSalesInvoice(DeliveryOrder deliveryOrder, ISalesInvoiceService _salesInvoiceService) { IList <SalesInvoice> salesInvoices = _salesInvoiceService.GetObjectsByDeliveryOrderId(deliveryOrder.Id); if (salesInvoices.Any()) { deliveryOrder.Errors.Add("Generic", "Sudah memiliki sales invoice"); } return(deliveryOrder); }