/**
  * 字段列表页.
  * 
  * @access public
  * @param integer $modId 模型 ID.
  * @return void
  */
 public function lists($modId)
 {
     $modId = intval($modId);
     if ($modId < 1) {
         $this->error('模型参数非法!');
     }
     // 验证是否为有效的模型.
     $modelField = new FieldModel();
     $moduleInfo = $modelField->checkValidModule($modId);
     if (FALSE === $moduleInfo) {
         $this->error('模型不存在或已被删除');
     }
     // 获取模型字段列表.
     $fieldList = $modelField->fetchList($modId);
     $this->assign(['fieldList' => $fieldList, 'moduleInfo' => $moduleInfo, 'fieldPrefix' => $this->_field_prefix])->display();
 }