ElementType.php

<?php

namespace Ukratio\TrouveToutBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\FormView;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

use Ukratio\TrouveToutBundle\Form\EventListener\AddOwnerElementSubscriber;
use Ukratio\TrouveToutBundle\Form\EventListener\AddChildElementSubscriber;
use Ukratio\TrouveToutBundle\Form\EventListener\AddElementSubscriber;

use Ukratio\TrouveToutBundle\Form\DataTransformer\TrueElementToElementTransformer;
use Ukratio\TrouveToutBundle\Entity\Element;
use Ukratio\TrouveToutBundle\Entity\Type;
use Ukratio\TrouveToutBundle\Entity\ConceptRepository;
use Ukratio\TrouveToutBundle\Service\CaractTypeManager;

use Doctrine\ORM\EntityManager;

class ElementType extends AbstractType
{
    private $em;
    private $conceptRepo;
    private $caractTypeManager;

    public function __construct(EntityManager $em, ConceptRepository $conceptRepo, CaractTypeManager $caractTypeManager)
    {
        $this->em = $em;
        $this->conceptRepo = $conceptRepo;
        $this->caractTypeManager = $caractTypeManager;
    }

    public function buildForm(FormBuilderInterface $builder, array $options)
    {

        $type = Type::getEnumerator($options['typeOfValue']);

        $builder->addEventSubscriber(new AddElementSubscriber($builder->getFormFactory(), $this->em, $this->conceptRepo, $type, $this->caractTypeManager));

        $builder->addEventSubscriber(new AddOwnerElementSubscriber($builder->getFormFactory(), $this->em));

        $builder->addEventSubscriber(new AddChildElementSubscriber($builder->getFormFactory(), $this->em, $type, $this->caractTypeManager));

        $builder->addModelTransformer(new TrueElementToElementTransformer($this->em));
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'Ukratio\TrouveToutBundle\Entity\Element',
            'constraintOnValue' => false,
            'typeOfValue' => 'name',
        ));
    }

    public function getName()
    {
        return 'TrouveTout_Element';
    }

    public function buildView(FormView $view, FormInterface $form, array $options)
    {
    }
}

part of js file

CaractsManager.prototype.getOrBuildChildForm = function (caractForm, index) {
	var childFormSelect;
	var type;
	var childFormSelectDiv;

	childFormSelect = this.getChildForm(caractForm);

	if (childFormSelect.length > 0) {
		return childFormSelect;
	} else {
		type = caractForm.find('[id$=type]').val();
		childFormSelectDiv = this.prototype_specify[type].replace(/childElement/g, 'caracts_' + (index).toString() + '_value_childElement');
		childFormSelectDiv = childFormSelectDiv.replace(/(name=.*?)\[.*?\]/g, '$1[caracts][' + (index).toString() + '][value][childElement]');
		caractForm.find('[id$=value_value]').parent().parent().parent().find('div:first').prepend(childFormSelectDiv);
		childFormSelect = this.getChildForm(caractForm);
		return childFormSelect;
	}
}