Mvc\Model::addBehavior

<?php

use Phalcon\Mvc\Model;
use Phalcon\Mvc\Model\Behavior\Timestampable;

class Robots extends Model
{

   public function initialize()
   {
    $this->addBehavior(new Timestampable(array(
            'onCreate' => array(
                    'field' => 'created_at',
                    'format' => 'Y-m-d'
            )
    )));
   }
}