Symfony2：如何在FormType中调用实体的存储库

我尝试调用我的实体的存储库Category以我的实体的类形​​式BonCommande，但是出现了这个错误：

注意：未定义的属性：C:\wamp\www\Symfony_test\src\Application\VehiculeBundle\Form\BonCommandeType.php第74行中的Application\VehiculeBundle\Form\BonCommandeType::$em

这是我的代码：

班上BonCommandeType.php:

namespace Application\VehiculeBundle\Form;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;
use Symfony\Component\Form\FormEvent;
use Symfony\Component\Form\FormEvents;
use Symfony\Component\Form\FormInterface;
use Application\VehiculeBundle\Entity\Category;

class BonCommandeType extends AbstractType
{
        /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */
       public function buildForm(FormBuilderInterface $builder, array $options)
    {
        // Name of the user
        $builder->add('observation', 'text');


    /* Add additional fields... */

    $builder->add('save', 'submit');

    // Add listeners
    $builder->addEventListener(FormEvents::PRE_SET_DATA, array($this, 'onPreSetData'));
    $builder->addEventListener(FormEvents::PRE_SUBMIT, array($this, 'onPreSubmit'));
}


protected function addElements(FormInterface $form, Category $categorie = null) {
    // Remove the submit button, we will place this at the end of the form later
    $submit = $form->get('save');
    $form->remove('save');


    // Add the province element
    $form->add('categorie', 'entity', array(
        'data' => $categorie,
        'empty_value' => '-- Choose --',
        'class' => 'ApplicationVehiculeBundle:Category',
        'property' => 'intitule',
        'mapped' => false)
    );

    // Cities are empty, unless we actually supplied a province
    $vehicules = array();
    if ($categorie) {
        // Fetch the cities from specified province
        $repo = $this->em->getRepository('ApplicationVehiculeBundle:Vehicule');
        $cities = $repo->findByCategory($categorie);
    }

    // Add the city element
    $form->add('vehicule', 'entity', array(
        'empty_value' => '-- Select a categorie first --',
        'class' => 'ApplicationVehiculeBundle:Vehicule',
        'choices' => $vehicules,
    ));

    // Add submit button again, this time, it's back at the end of the form
    $form->add($submit);
}


function onPreSubmit(FormEvent $event) {
    $form = $event->getForm();
    $data = $event->getData();

    // Note that the data is not yet hydrated into the entity.
    $categorie = $this->em->getRepository('ApplicationVehiculeBundle:Category')->find($data['categorie']);
    $this->addElements($form, $categorie);
}


function onPreSetData(FormEvent $event) {
    $account = $event->getData();
    $form = $event->getForm();

    // We might have an empty account (when we insert a new account, for instance)
    $categorie = $account->getVehicule() ? $account->getVehicule()->getCategorie() : null;
    $this->addElements($form, $categorie);
}
...
}

这是导致错误的指令：

$categorie = $this->em->getRepository('ApplicationVehiculeBundle:Category')->find($data['categorie']);

FormComponent是一个独立的组件，它不提供任何entityManager可供使用。你必须注入它或传递它$options如果你想使用它..

在你的情况下，如果你直接将它传递给类型是正确的__construct或路过$options数组或将您的类型声明为服务并向其注入实体管理器：

class BonCommandeType extends AbstractType
{
    private $em;

    public function __construct(EntityManagerInterface $em)
    {
        $this->em = $em;
    }

    ...
}

or

$this->createForm(TYPE, DATA, ['em' => $em]);