gistfile1.php

<?php

namespace Ma7shy\BackendBundle\Form\Type\Field;

use Doctrine\ODM\MongoDB\DocumentManager;
use Ma7shy\BackendBundle\Form\Transformer\ObjectToDocumentTransformer;
use Ma7shy\BackendBundle\Form\Transformer\ObjectToRefTransformer;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\OptionsResolver\OptionsResolverInterface,
    Symfony\Component\Routing\Router;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Routing\Generator\UrlGeneratorInterface;

class UserAjaxField extends AbstractType
{
    /** @var $router UrlGeneratorInterface */
    protected $router;
    /** @var $em DocumentManager */
    protected $dm;

    /**
     * @param UrlGeneratorInterface $router
     * @param DocumentManager       $dm
     */
    function __construct(UrlGeneratorInterface $router, DocumentManager $dm)
    {
        $this->router = $router;
        $this->dm     = $dm;
    }


    /**
     * @param FormBuilderInterface $builder
     * @param array                $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->addModelTransformer(
            new ObjectToDocumentTransformer($this->dm, 'Ma7shy\UserBundle\Document\User', 'id', 'fullName', false)
        );
    }

    /**
     * @param OptionsResolverInterface $resolver
     */
    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(
            [
                'label'       => 'User',
                'configs'     => [
                    'width' => '300px',
                    'ajax'  => [
                        'url'      => $this->router->generate('ma7shy_backend_users_userautocomplete', [], true),
                        'type'     => 'GET',
                        'dataType' => 'json',
                        'data'     => "function (term, page) {
                            return {
                            term: term,
                            page_limit: 5,
                            page: page,
                            };
                            }",
                        'results'  => "function (data, page) {
                            return {results: data};
                            }"
                    ],
                ],
                'class'       => 'Ma7shy\UserBundle\Document\user',
                'empty_value' => '-- Select Creator --'
            ]
        );
    }

    /**
     * @return null|string|\Symfony\Component\Form\FormTypeInterface
     */
    public function getParent()
    {
        return 'thrace_select2_ajax';
    }

    /**
     * @return string
     */
    public function getName()
    {
        return 'user_ajax_type';
    }

}

gistfile2.php

<?php


namespace Ma7shy\BackendBundle\Form\Transformer;

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Util\Inflector;
use Symfony\Component\Form\DataTransformerInterface;
use Symfony\Component\Form\Exception\TransformationFailedException;
use Doctrine\Common\Persistence\ObjectManager;

/**
 * Class ObjectToDocumentTransformer
 *
 * @package Ma7shy\BackendBundle\Form\Transformer
 */
class ObjectToDocumentTransformer implements DataTransformerInterface
{
    /** @var $om ObjectManager */
    private $om;
    /** @var $objectRepository string */
    private $objectRepository;
    /** @var $identifier null */
    private $identifier;
    /** @var  $displayPropery null */
    private $displayProperty;
    /** @var $multiple boolean */
    private $multiple;

    /**
     * @param ObjectManager $om
     * @param               $objectRepository
     * @param null          $identifier
     * @param null          $displayProperty
     * @param               $multiple
     */
    public function __construct(
        ObjectManager $om,
        $objectRepository,
        $identifier = null,
        $displayProperty = null,
        $multiple
    ) {
        $this->om               = $om;
        $this->objectRepository = $objectRepository;
        $this->identifier       = $identifier;
        $this->displayProperty  = !isset($displayProperty) ? $identifier : $displayProperty;
        $this->multiple         = $multiple;
    }

    /**
     * @param mixed $entity
     *
     * @return mixed|string
     */
    public function transform($entity)
    {
        if ($this->multiple) {
            if (!$entity instanceof \ArrayAccess && !is_array($entity)) {
                return '';
            }

            $entities = [];
            foreach ($entity as $singleId) {
                $entities[] = $this->transformSingle($singleId);
            }

            return implode(', ', $entities);
        } else {
            if (is_null($entity) || !is_object($entity)) {
                return '';
            }

            return $this->transformSingle($entity);
        }
    }

    /**
     * @param $entity
     *
     * @return mixed|string
     */
    public function transformSingle($entity)
    {
        $meta = $this->om->getClassMetadata(get_class($entity));
        if ($this->identifier !== null) {
            $getter = 'get' . Inflector::camelize($this->identifier);

            return $entity->$getter();
        }

        $identifier = current($meta->getIdentifierValues($entity));

        if ($identifier === null) {
            return '';
        }

        return $identifier;
    }

    /**
     * @param mixed $id
     *
     * @return ArrayCollection|mixed|null|object
     */
    public function reverseTransform($id)
    {
        if (!$id) {
            return null;
        }
        if ($this->multiple) {
            if (strpos($id, ',') === false) {
                return new ArrayCollection([$this->reverseTransformSingle($id)]);
            } else {
                $id = array_unique(array_filter(array_map('trim', explode(',', $id))));
            }
            $entities = new ArrayCollection();
            foreach ($id as $singleId) {
                $entities->add($this->reverseTransformSingle($singleId));
            }

            return $entities;
        } else {
            return $this->reverseTransformSingle($id);
        }
    }

    /**
     * @param $id
     *
     * @return object
     * @throws \Symfony\Component\Form\Exception\TransformationFailedException
     */
    public function reverseTransformSingle($id)
    {
        if ($this->identifier !== null) {
            $findOneBy = 'findOneBy' . Inflector::camelize($this->identifier);
            $entity    = $this->om->getRepository($this->objectRepository)->$findOneBy($id);
        } else {
            $entity = $this->om->getRepository($this->objectRepository)->find($id);
        }

        if (null === $entity) {
            throw new TransformationFailedException(sprintf(
                'An entity with id "%s" does not exist!',
                $id
            ));
        }

        return $entity;
    }
}