Region.php

<?php
#/app/Model/Region.php
class Region extends AppModel {

    public $displayField        = 'region';
    public $hasAndBelongsToMany = array('Order');

    public $validate = array(
        'region' => array(
            'rule' => array('notEmpty'),
            'required' => true,
            'message' => 'inserire la regione'
        )
    );
}