Symfony mongo search service

controller

public function searchAction(Request $request)
    {
        $search = $request->query->get('s');
        $searchResult = $this->get('booking.core.service.search_service')
            ->searchByDocument(
                'NewsBundle\Document\News',
                [
                    '_id',
                    'type',
                    'title',
                    'content',
                    'author',
                ],
                $search
            );

SearchService

<?php

namespace CoreBundle\Service;

use Doctrine\ODM\MongoDB\DocumentManager;
use Doctrine\ODM\MongoDB\Query\Query;

class SearchService
{
    private $dm;

    public function __construct(DocumentManager $documentManager)
    {
        $this->dm = $documentManager;
    }

    /**
     * @param null $documentName
     * @param array $fields
     * @param string $search
     * @return bool|Query
     */
    public function searchByDocument($documentName = null, array $fields = [], $search = '')
    {
        $search = preg_quote(trim($search));

        if (empty($search)) {
            return false;
        }
        if (0 == count($fields)) {
            return false;
        }

        $query = $this->dm
            ->createQueryBuilder($documentName);

        foreach ($fields as $filed) {
            if (('_id' === $filed) && (1 === preg_match("/^[abcdef\\d]{24}$/", $search))) {
                $query
                    ->addOr($query->expr()->field($filed)->equals(new \MongoId($search)));
            } else {
                $query
                    ->addOr($query->expr()->field($filed)->equals(new \MongoRegex('/.*'.htmlspecialchars($search).'.*/i')));
            }
        }

        return $query
//            ->hydrate(false)
            ->getQuery();
    }
}

services

<service id="booking.core.service.search_service"
         class="CoreBundle\Service\SearchService">
    <argument type="service" id="doctrine.odm.mongodb.document_manager"/>
</service>