我有一个城市和选民实体之间的一对多关系。我想将实体字段（下拉列表中的成千上万条记录）转换为文本输入，以便当用户开始输入2个字母时可以实现JQuery自动完成功能。两周后，我成功创建了DataTransformer，它将实体字段转换为文本输入。现在我的问题是我仍在学习JQuery
/ Ajax，并且困惑如何以Symfony2形式实现它。

//formtype.php


private $entityManager;

public function __construct(ObjectManager $entityManager)
{
  $this->entityManager = $entityManager;
}
$builder
        ->add('address', null, array(
        'error_bubbling' => true
      ))
        ->add('city', 'text', array(
        'label' => 'Type your city',
        //'error_bubbling' => true,
        'invalid_message' => 'That city you entered is not listed',
      ))
 $builder->get('city')
      ->addModelTransformer(new CityAutocompleteTransformer($this->entityManager));

//datatransformer.php

class CityAutocompleteTransformer implements DataTransformerInterface
{
private $entityManager;

public function __construct(ObjectManager $entityManager)
{
    $this->entityManager = $entityManager;
}

public function transform($city)
{
    if (null === $city) {
        return '';
    }

    return $city->getName();
}

public function reverseTransform($cityName)
{
    if (!$cityName) {
        return;
    }

    $city = $this->entityManager
        ->getRepository('DuterteBundle:City')->findOneBy(array('name' => $cityName));

    if (null === $city) {
        throw new TransformationFailedException(sprintf('There is no "%s" exists',
            $cityName
        ));
    }

    return $city;
 }
}

//controller.php

public function createAction(Request $request)
{
    $entity = new Voters();
    $form = $this->createCreateForm($entity);
    $form->handleRequest($request);

    $validator = $this->get('validator');
    $errors = $validator->validate($entity);
    if ($form->isValid()) {
        $em = $this->getDoctrine()->getManager();
        $em->persist($entity);
        $em->flush();


        $this->addFlash('danger', 'You are successfully added!, Welcome to the growing Supporters, dont forget to share and invite this to your friends and relatives, click share buttons below, have a magical day!');

        //return $this->redirect($this->generateUrl('voters_show', array('id' => $entity->getId())));
        return $this->redirect($this->generateUrl('voters_list'));
    } else {

        $this->addFlash('danger', 'Oppss somethings went wrong, check errors buddy!');

        return $this->render('DuterteBundle:Voters:neww.html.twig', array(
            'entity' => $entity,
            'form'   => $form->createView(),
        ));
    }
}

/**
 * Creates a form to create a Voters entity.
 *
 * @param Voters $entity The entity
 *
 * @return \Symfony\Component\Form\Form The form
 */
private function createCreateForm(Voters $entity)
{   
    $entityManager = $this->getDoctrine()->getManager();
    $form = $this->createForm(new VotersType($entityManager), $entity, //here i passed the entity manager to make it work
array(
        'action' => $this->generateUrl('voters_create'),
        'method' => 'POST',
    ));

    $form->add('submit', 'submit', array(
        'label' => 'I Will Vote Mayor Duterte'
    ));

    return $form;
}

使用此代码，当用户输入的城市名称与数据库中已保存的名称不匹配时，我可以成功创建一个新的选民并抛出验证错误（表单类型中的invalid_message）。我现在缺少的是我想要实现当用户键入至少两个字母时，jQuery自动完成

树枝部分

//twig.php

  {{ form_start(form, {attr: {novalidate: 'novalidate'}} ) }}
        {{ form_errors(form) }}
        {{ form_row(form.comments,{'attr': {'placeholder': 'Why You Want '}}) }}
        {{ form_row(form.email,{'attr': {'placeholder': 'Email is optional, you may leave it blank.But if you want to include your email, make sure it is your valid email '}}) }}
        {{ form_end(form) }}

如您所见，表单本身除了City字段外还由许多字段组成。在这里，City字段是一个下拉列表，由数据库中的一千多个条目组成。我可以使用DataTransformer将这个下拉列表成功转换为文本字段。因此，这里的问题是如何在具有许多字段的此表单内实现JQuery
Autocomplete。

任何帮助表示赞赏

更新资料

根据用户Frankbeen的回答，我在控制器内添加了一个动作

public function autocompleteAction(Request $request)
{
    $names = array();
    $term = trim(strip_tags($request->get('term')));

    $em = $this->getDoctrine()->getManager();

    $entities = $em->getRepository('DuterteBundle:City')->createQueryBuilder('c')
       ->where('c.name LIKE :name')
       ->setParameter('name', '%'.$term.'%')
       ->getQuery()
       ->getResult();

    foreach ($entities as $entity)
    {
        $names[] = $entity->getName()."({$entity->getProvince()})";
    }

    $response = new JsonResponse();
    $response->setData($names);

    return $response;
}

还有js文件

{% block javascripts %}
{{ parent() }}
<script src="//code.jquery.com/ui/1.10.3/jquery-ui.js"></script>
<script>
    $(function() {
        function log( message ) {
            $( "<div>" ).text( message ).prependTo( "#log" );
            $( "#log" ).scrollTop( 0 );
        }

        $( "#project_bundle_dutertebundle_voters_city").autocomplete({
            source: "{{ path('city_autocomplete') }}",
            minLength: 2,
            select: function( event, ui ) {
            log( ui.item ?
                "Selected: " + ui.item.value + " aka " + ui.item.id :
                "Nothing selected, input was " + this.value );
            }
        });
    });
</script>
{% endblock %}

在这种情况下，

  $( "#project_bundle_dutertebundle_voters_city").autocomplete({

该部分实际上是Symfony2在呈现表单时提供的城市字段的默认ID.JQuery自动完成现在可以正常工作，但是问题是，我无法保存所选的选项，同时触发了我在FormType.php中创建的invalid_message验证以及单击提交按钮时的JQuery脚本

选项：Basista（Pangasinan Province）又名未定义

告诉您所选值的ID未定义

$( "#project_bundle_dutertebundle_voters_city").autocomplete({
            source: "{{ path('city_autocomplete') }}",
            minLength: 2,
            select: function( event, ui ) {
            log( ui.item ?
                "Selected: " + ui.item.value + " aka " + ui.item.id ://this throw undefined
                "Nothing selected, input was " + this.value );
            }
        });