aimeric/DefaultController.php

## DefaultController.php
<?php

/* src/AppBundle/Controller/DefaultController */

namespace AppBundle\Controller;

use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;

use AppBundle\Entity\Entity;
use AppBundle\Repository\EntityRepository;

class DefaultController extends Controller
{
  /**
   * Creates a new ActionItem entity.
   *
   * @Route("/search", name="ajax_search")
   * @Method("GET")
   */
  public function searchAction(Request $request)
  {
      $em = $this->getDoctrine()->getManager();

      $requestString = $request->get('q');

      $entities =  $em->getRepository('AppBundle:Entity')->findEntitiesByString($requestString);

      if(!$entities) {
          $result['entities']['error'] = "keine Einträge gefunden";
      } else {
          $result['entities'] = $this->getRealEntities($entities);
      }

      return new Response(json_encode($result));
  }

  public function getRealEntities($entities){

      foreach ($entities as $entity){
          $realEntities[$entity->getId()] = $entity->getFoo();
      }

      return $realEntities;
  }
}

## EntityRepository.php
<?php

/* src/AppBundle/Repository/EntityRepository */

namespace AppBundle\Repository;

/**
 * EntityRepository
 *
 * This class was generated by the Doctrine ORM. Add your own custom
 * repository methods below.
 */
class EntityRepository extends \Doctrine\ORM\EntityRepository
{
    public function findEntitiesByString($str){
        return $this->getEntityManager()
            ->createQuery(
                'SELECT e
                FROM AppBundle:Entity e
                WHERE e.foo LIKE :str'
            )
            ->setParameter('str', '%'.$str.'%')
            ->getResult();
    }
}

## template.html.twig
<!DOCTYPE html>
<html>

<!-- app/Resources/views/template.html.twig -->

<head>
	<title></title>
</head>
<body>
  <div class="sidebar-search">
      <div class="input-group custom-search-form">
          <input type="text" id="search" class="form-control" placeholder="Suche...">
      </div>
      <!-- /input-group -->
  </div>
  <ul class="nav" id="side-menu">
      <li>
          <a href="#"> Entities<span class="fa arrow"></span></a>
          <ul class="nav nav-second-level" id="entitiesNav">
          </ul>
      </li>
  </ul>
</body>
</html>

<!-- jQuery is necessary -->
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>

<script type="text/javascript">
    jQuery(document).ready(function() {

        var searchRequest = null;

        $("#search").keyup(function() {
            var minlength = 3;
            var that = this;
            var value = $(this).val();
            var entitySelector = $("#entitiesNav").html('');

            if (value.length >= minlength ) {
                if (searchRequest != null)
                    searchRequest.abort();
                searchRequest = $.ajax({
                    type: "GET",
                    url: "{{ path('ajax_search') }}",
                    data: {
                        'q' : value
                    },
                    dataType: "text",
                    success: function(msg){
                        //we need to check if the value is the same
                        if (value==$(that).val()) {
                            var result = JSON.parse(msg);
                            $.each(result, function(key, arr) {
                                $.each(arr, function(id, value) {
                                    if (key == 'entities') {
                                        if (id != 'error') {
                                            entitySelector.append('<li><a href="/daten/'+id+'">'+value+'</a></li>');
                                        } else {
                                            entitySelector.append('<li class="errorLi">'+value+'</li>');
                                        }
                                    }
                                });
                            });
                        }
                     }
                });
            }
        });
    });
</script>
	<?php

	/* src/AppBundle/Controller/DefaultController */

	namespace AppBundle\Controller;

	use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
	use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
	use Symfony\Bundle\FrameworkBundle\Controller\Controller;
	use Symfony\Component\DependencyInjection\ContainerInterface;
	use Symfony\Component\HttpFoundation\Request;
	use Symfony\Component\HttpFoundation\Response;

	use AppBundle\Entity\Entity;
	use AppBundle\Repository\EntityRepository;

	class DefaultController extends Controller
	{
	/**
	* Creates a new ActionItem entity.
	*
	* @Route("/search", name="ajax_search")
	* @Method("GET")
	*/
	public function searchAction(Request $request)
	{
	$em = $this->getDoctrine()->getManager();

	$requestString = $request->get('q');

	$entities = $em->getRepository('AppBundle:Entity')->findEntitiesByString($requestString);

	if(!$entities) {
	$result['entities']['error'] = "keine Einträge gefunden";
	} else {
	$result['entities'] = $this->getRealEntities($entities);
	}

	return new Response(json_encode($result));
	}

	public function getRealEntities($entities){

	foreach ($entities as $entity){
	$realEntities[$entity->getId()] = $entity->getFoo();
	}

	return $realEntities;
	}
	}
	<?php

	/* src/AppBundle/Repository/EntityRepository */

	namespace AppBundle\Repository;

	/**
	* EntityRepository
	*
	* This class was generated by the Doctrine ORM. Add your own custom
	* repository methods below.
	*/
	class EntityRepository extends \Doctrine\ORM\EntityRepository
	{
	public function findEntitiesByString($str){
	return $this->getEntityManager()
	->createQuery(
	'SELECT e
	FROM AppBundle:Entity e
	WHERE e.foo LIKE :str'
	)
	->setParameter('str', '%'.$str.'%')
	->getResult();
	}
	}
	<!DOCTYPE html>
	<html>

	<!-- app/Resources/views/template.html.twig -->

	<head>
	<title></title>
	</head>
	<body>
	<div class="sidebar-search">
	<div class="input-group custom-search-form">
	<input type="text" id="search" class="form-control" placeholder="Suche...">
	</div>
	<!-- /input-group -->
	</div>
	<ul class="nav" id="side-menu">
	<li>
	<a href="#"> Entities<span class="fa arrow"></span></a>
	<ul class="nav nav-second-level" id="entitiesNav">
	</ul>
	</li>
	</ul>
	</body>
	</html>

	<!-- jQuery is necessary -->
	<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>

	<script type="text/javascript">
	jQuery(document).ready(function() {

	var searchRequest = null;

	$("#search").keyup(function() {
	var minlength = 3;
	var that = this;
	var value = $(this).val();
	var entitySelector = $("#entitiesNav").html('');

	if (value.length >= minlength ) {
	if (searchRequest != null)
	searchRequest.abort();
	searchRequest = $.ajax({
	type: "GET",
	url: "{{ path('ajax_search') }}",
	data: {
	'q' : value
	},
	dataType: "text",
	success: function(msg){
	//we need to check if the value is the same
	if (value==$(that).val()) {
	var result = JSON.parse(msg);
	$.each(result, function(key, arr) {
	$.each(arr, function(id, value) {
	if (key == 'entities') {
	if (id != 'error') {
	entitySelector.append('<li><a href="/daten/'+id+'">'+value+'</a></li>');
	} else {
	entitySelector.append('<li class="errorLi">'+value+'</li>');
	}
	}
	});
	});
	}
	}
	});
	}
	});
	});
	</script>