DataSource Grid Records Exporting using getFirst and getNext methods in ax 2012

        JourTransEFT   =    LedgerJournalTransEFT_ds.getFirst( 1, false );
        while (JourTransEFT && JourTransEFT.EFTPaymentId == "")
        {
            row++;
            xlsWorkSheet.cells().item(row,1).value(JourTransEFT.Voucher);
            xlsWorkSheet.cells().item(row,2).value(JourTransEFT.VendName);
         
            JourTransEFT = CICLedgerJournalTransEFT_ds.getNext();
        }