<Button onclick = "return fun()"/>

<script>
  function fun(){
    var CheckBox = document.getElementsByName('checkBox[]');//获取所有的checkBox
    var count=0;
    for(i=0;i < CheckBox.length;i++){
      if(CheckBox[i].checked == true){                
        count++;
      }
    }
    if(count == 0 ){
      var errorMeg = document.getElementById('HomeworkTrConfig_flag_em_');
      errorMeg.style.display = "";
      errorMeg.innerHTML="请至少选择一项";      
      return false;
    }else{
      return true;
    }
  }
</script>

$form = $this->beginWidget('CActiveForm',array(
    'id' => 'add_host',
    'enableAjaxValidation' => false,
    'enableClientValidation' => true,
    'clientOptions' => array(
        'validateOnSubmit' => true //在这个位置做验证
      ),
    'focus' => array($model,'ip')
  ));
?>