RE: Override lookup method in AX 2012

 Query                   query = new Query();

            QueryBuildDataSource    queryBuildDataSource;

            SysTableLookup  sysTableLookup = sysTableLookup::newParameters(tableNum(InventSite), this);

            ;

            sysTableLookup.addLookupfield(fieldNum(InventSite, SiteId), true);

            sysTableLookup.addLookupfield(fieldNum(InventSite, Name));

            queryBuildDataSource = query.addDataSource(tableNum(InventSite));

            queryBuildDataSource.addSortField(fieldnum(InventSite, SiteId));

            queryBuildDataSource.addOrderByField(fieldnum(InventSite, Name));

            queryBuildDataSource.orderMode(OrderMode::GroupBy);//Used to Group the Field Value

            sysTableLookup.parmQuery(query);

            sysTableLookup.performFormLookup();

class LookupFormClass
{
    public InventSiteName getInventSiteName(InventSiteId _inventSiteId)
    {
        return InventSite::find(_inventSiteId).Name;
    }

}

public boolean modified()
        {
            boolean ret;
            LookupFormClass obj;

            ret = super();

            if (ret)
            {
                obj = new LookupFormClass();
                this.text(obj.getInventSiteName(this.text()));
            }

            return ret;
        }