Onethink used 8421 code in checkbox, and if it is extra values must add processing function in logic model.

Like that:

Application\Admin\Logic\ProductLogic.class.php

 protected $_auto = array(

  array('duoxuan', 'getDuoxuan', self::MODEL_BOTH, 'callback'),

 );

    protected function getDuoxuan(){

        $duoxuan = I('post.duoxuan');

        if(!is_array($duoxuan)){

            return 0;

        }else{

            $pos = 0;

            foreach ($duoxuan as $key=>$value){

                $pos += $value;		//将各个推荐位的值相加

            }

            return $pos;

        }

    }