public static boolean isInvoiceAlreadyStored(Invoice invoice) { List<Invoice> results = getObjectsByRow(Invoice.class, "po_number", EqualityRelation.E, invoice.getPoNumber()); boolean emptySet = results.isEmpty(); if (!emptySet) { Invoice oldInvoice = results.get(0); invoice.setId(oldInvoice.getId()); saveOrUpdateInvoice(invoice); return true; } return false; }