Filtering the Location Id(lookup) where the purpose of the location(LocationRole) is 'Service'

        Query        query = new Query();
        QueryBuildDataSource    qbds;
        QueryBuildDataSource    qbdsJoin;
        QueryBuildDataSource    qbdsJoin2;
        QueryBuildDataSource    qbdsJoin3;
        QueryBuildDataSource    qbdsJoin4;
        int64 locationroleid = 5637144580;
        SalesTable salestable;
        SysTableLookup          sysTableLookup = sysTableLookup::newParameters( tableNum(LogisticsLocation),sender);
        QueryRun queryrun;
        qbds= query.addDataSource( tableNum(LogisticsLocation));
        qbdsJoin= qbds.addDataSource( tableNum(DirPartyLocation));
        qbdsJoin2= qbdsJoin.addDataSource( tableNum(DirPartyTable));
        qbdsJoin3 = qbdsJoin2.addDataSource( tableNum(CustTable));
        qbdsJoin4  = qbdsJoin.addDataSource( tableNum(DirPartyLocationRole));

        qbdsJoin.relations( true); //If relations are defined in the table then set it to true.
        qbdsJoin2.relations( true);
        qbdsJoin3.relations( true);

        qbdsJoin4.relations( true);

        FormRun form = sender.formRun();
        FormDataSource salestable_ds = form.dataSource(formDataSourceStr(SalesTable,SalesTable)) as FormDataSource;
        salestable= salestable_ds.cursor();

        sysTableLookup.addLookupfield(fieldNum(LogisticsLocation,LocationId));
        sysTableLookup.addLookupfield(fieldnum(LogisticsLocation,Description));

        qbdsJoin3.addRange(fieldNum(CustTable,AccountNum)).value(queryValue(salestable.CustAccount));
        qbdsJoin4.addRange(fieldNum(DirPartyLocationRole, locationRole)).value(int2Str(locationroleid));
        sysTableLookup.parmQuery(query);
        sysTableLookup.performFormLookup();


        FormControlCancelableSuperEventArgs ce = e as FormControlCancelableSuperEventArgs;
        //cancel super() to prevent error.
        ce.CancelSuperCall();