Cakephp select validation

http://www.happyquality.com/2013/08/26/2696.htm

http://book.cakephp.org/2.0/ja/models/data-validation.html

public $validate = array(

        'user_id' => array(

            'notempty' => array(

                'rule' => array('multiple'),

                'message' => '担当者は必ず１人以上選択してください',

                //'allowEmpty' => false,

                //'required' => false,

                //'last' => false, // Stop validation after this rule

                //'on' => 'create', // Limit validation to 'create' or 'update' operations

            ),

        ),

);