Using getRepository on a FormType

NomeDoSeuTypeType.php

<?php
namespace AppBundle\Form\Type;

use Doctrine\Common\Persistence\ObjectManager;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;

class NomeDoSeuTypeType extends AbstractType
{
    /**
     * @var ObjectManager
     */
    private $objectManager;

    public function __construct(ObjectManager $objectManager)
    {
        $this->objectManager = $objectManager;
    }
    
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->addEventListener(
          FormEvents::PRE_SUBMIT,
          function(FormEvent $event) {
            ...
            $this-objectManager->getRepository('YourEntity')
            ...
          }
        );
    }
}

services.yml

app.form.type.nome_do_seu_type:
       class: AppBundle\Form\Type\NomeDoSeuTypeType
       arguments: ['@doctrine.orm.entity_manager']
       tags:
           - { name: form.type, alias: nome_do_seu_type }