Symfony 2表单字段集合

I am currently develloping a web site where i have a tag system to tag reviews. Each review has several tag in a many to many relation with a tag class

     /**
 * Review
 *
 * @ORM\Table()
 * @ORM\Entity(repositoryClass="UnicornumMetalum\EntityBundle\Entity\ReviewRepository")
 */
 class Review
     /**
     * @ORM\ManyToMany(targetEntity="Tag")
     */
    private $tags;
}

I'd like to add a front office form where i could use something like the sonata sonata_type_model form field.

In fact i want exactly that sonata form field, because it work just like i'd want it in my front office (exactly lke the stack overflow tag field).

But the symfony form type don't allow it somehow the colloection or entity form fileds always end up prompting either nothing or you have to add tons of javascript and in the the end the result is ugly as hell (and not good to use).

Do anyone know how to do so with symfony ?

Thanks for reading