ViewModel 后面的几个表没有字段就显示不出，希望有几个表就显示几个表的字段，怎么办？
class FaultreportViewModel extends ViewModel {
public $viewFields = array(
'Faultreport'=>array('fid','reporter','content','reporttime','username','eqid','flevel'),
'base'=>array('eqname', 'team','building','_on'=>'Faultreport.eqid=base.eqid'),
//'Send'=>array('sender', '_on'=>'Faultreport.fid=Send.fid'),