EventSubscriber中的Symfony访问实体管理器

Question

I have an Employer profile form and I am trying to link the State where Employer is located at with a City this part is working alright but the FormType got so long and this feature will be required at other places of the website so I decided to move this logic inside an EventSubscriber and reuse it where ever I need it.

Problem I am having is I am trying to wrap my head around how to inject EntityManager inside the EventSubscriber class.

I know I can add the following code inside my services.yml and that should do it buts its not working.

app.form.location:
    class: AppBundle\Form\EventListener\AddStateFieldSubscriber
    arguments: ['@doctrine.orm.entity_manager']
    tags:
        - { name: kernel.event_subscriber }

This is my EmployerProfileType where I am calling my addEventSubscriber which is AddStateFieldSubscriber()

class EmployerProfileType extends AbstractType
{
    protected $em;

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

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('firstName', TextType::class)
            ->add('lastName', TextType::class)
            ->add('companyName', TextType::class)
            ->add('companyProfile', TextareaType::class)
            ->add('companyLogo', FileType::class, array(
                'data_class' => null
            ));
        $builder->addEventSubscriber(new AddStateFieldSubscriber());

    }


    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'AppBundle\Entity\EmployerProfile',

        ));
    }


    public function getName()
    {
        return 'app_bundle_emp_profile_type';
    }
}

This is my AddStateFieldSubscriber class where I need access to EntityManager

class AddStateFieldSubscriber implements EventSubscriberInterface
{

    protected $em;

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

    public static function getSubscribedEvents()
    {
        // Tells the dispatcher that you want to listen on the form.pre_set_data
        // event and that the preSetData method should be called.
        return array(
            FormEvents::PRE_SET_DATA => 'onPreSetData',
            FormEvents::PRE_SUBMIT => 'onPreSubmit'
            );
    }
    protected function addElements(FormInterface $form, States $province = null)
    {
        // Remove the submit button, we will place this at the end of the form later
        // Add the province element
        $form->add('state', EntityType::class, array(
                'data' => $province,
                'placeholder' => 'provide_state',
                'class' => 'AdminBundle\Entity\States',
                'mapped' => false)
        );
        // Cities are empty, unless we actually supplied a province
        $cities = array();
        if ($province) {
            // Fetch the cities from specified province
            $repo = $this->em->getRepository('AdminBundle:Cities');
            $cities = $repo->findByStates($province, array('name' => 'asc'));
        }
        // Add the city element
        $form->add('city', EntityType::class, array(
            'placeholder' => 'provide_state_first',
            'class' => 'AdminBundle\Entity\Cities',
            'choices' => $cities,
        ));

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

        // Note that the data is not yet hydrated into the entity.
        $province = $this->em->getRepository('AdminBundle:States')->find($data['state']);
        $this->addElements($form, $province);
    }
    function onPreSetData(FormEvent $event) {
        $account = $event->getData();
        $form = $event->getForm();

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

The error I get is

Catchable Fatal Error: Argument 1 passed to AppBundle\\Form\\EventListener\\AddStateFieldSubscriber::__construct() must be an instance of Doctrine\\ORM\\EntityManager, none given, called in /Users/shairyar/Sites/clickjobboard/src/AppBundle/Form/EmployerProfileType.php on line 48 and defined

I am injecting EntityManager via service then why do I get this error?

If inside EmployerProfileType I replace

$builder->addEventSubscriber(new AddStateFieldSubscriber(); to $builder->addEventSubscriber(new AddStateFieldSubscriber($this->em));

then things start working fine.

I thought in Symfony we are supposed to inject the dependencies by creating services? So how can I inject EntityManager inside my AddStateFieldSubscriber() class

What am i doing wrong? may be I am over thinking about it.

Will appreciate any feedback.

Answer 1

I think you need to tag your AddStateFieldSubscriber as kernel.event_subscriber.

Then the binding inside the form in not needed at all.

Instead you need to check for the correct form, and jump out of the event listener method if the form is not one of your forms using that subscriber, since the Event would be triggered on any form then, not only the EmployerProfileType form.