Create Mandatory with message using x++

Create Mandatory with message using x++ :

 if (!CreditCardTable.Zipcode)

{

warning("Zipcode must be filled in!");

ret = false;

}

public boolean fetch()

{

    Query       _query = new Query(this.query());

    QueryRun    _queryRun;

    boolean ret;

    ;

    //ret = super();

    parmTtd = dialogTtd.value();

    if (parmTtd == NoYes::No)

    {

        TtdImage.visible(false);

    }

    else

    {

        TtdImage.visible(true);

    }

    _query.dataSourceTable(tableNum(VendPurchOrderJour)).addRange(fieldNum(VendPurchOrderJour, PurchId)).value(_vendPurchOrderJour.PurchId);

    _query.dataSourceTable(tableNum(VendPurchOrderJour)).addRange(fieldNum(VendPurchOrderJour, PurchTableVersion)).value(SysQuery::value(_vendPurchOrderJour.PurchTableVersion));

    //_query.dataSourceTable(tableNum(PurchLineAllVersions)).addRange(fieldNum(PurchLineAllVersions, ItemId)).value(SysQuery::value(_purchLineAllVersions.ItemId));

    _queryRun = new QueryRun(_query);

    //rowNum = 1;

    while (_queryRun.next())

    {

        if (_queryRun.changed(tableNum(VendPurchOrderJour)))

        {

            _vendPurchOrderJour = _queryRun.get(tableNum(VendPurchOrderJour));

            element.send(_vendPurchOrderJour);

            Keterangan = PurchParmTable::findPurchId(_vendPurchOrderJour.PurchId, _vendPurchOrderJour.ParmId).TECKeterangan;

            NoFax = PurchParmTable::findPurchId(_vendPurchOrderJour.PurchId, _vendPurchOrderJour.ParmId).TECNoFax;

            Payment = PurchTable::find(_vendPurchOrderJour.PurchId).Payment;

            //totalQty += CorrectPackingSlip.CorrectionQty;

        }

        if (_queryRun.changed(tableNum(PurchLineAllVersions)))

        {

            _purchLineAllVersions = _queryRun.get(tableNum(PurchLineAllVersions));

            if (_purchLineAllVersions.ItemId != TMPItemId)

            {

                element.send(_purchLineAllVersions);

                TMPItemId = _purchLineAllVersions.ItemId;

            }

        }

        //rowNum++;

    }

    if (row < 10)

    {

        while ((10-row) != 0)

        {

             element.execute(1);

             row++;

        }

    }

    if (row == 10)

    {

        element.execute(2);

        element.newPage();

    }

    return true;

}