Symfony - Inject Entity Manager in EventSubscriber of form

Question

This is the first time I am working with EventListener of a form so I am struggling on how to inject EntityManager in it.

I have this formType called UserType<

Answer 1

It's because, you pass new instance of AddDepartmentDegreeCourseFieldSubscriber when building form. You need to pass instance from service container.

use AppBundle\Form\EventListener\AddDepartmentDegreeCourseFieldSubscriber;

class UserType extends AbstractType
{
    private $addDepartmentDegreeCourseFieldSubscriber;

    public function __construct(AddDepartmentDegreeCourseFieldSubscriber $subscriber)
    {
        $this->addDepartmentDegreeCourseFieldSubscriber = $subscriber;
    }

    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->addEventSubscriber($this->addDepartmentDegreeCourseFieldSubscriber);
    }
}

# app/config/services.yml
services:
    app.department_course_degree_subscriber:
        class: AppBundle\Form\EventListener\AddDepartmentDegreeCourseFieldSubscriber
        arguments: ["@doctrine.orm.entity_manager"]
        tags:
            - { name: kernel.event_subscriber }

    app.form.type.my_user_form:
        class: AppBundle\Form\UserType
        arguments: [ "@app.department_course_degree_subscriber" ]
        tags:
            - { name: form.type }