Content controller for easy admin to create fields of empty entity.

ContentController.php

<?php

namespace App\Controller\Admin;

use Doctrine\ORM\OptimisticLockException;
use Doctrine\ORM\ORMException;
use EasyCorp\Bundle\EasyAdminBundle\Controller\AdminController;

class ContentController extends AdminController
{
    protected function editAction()
    {
        $entity = $this->em->getRepository($this->entity['class'])->findOneBy([]);

        if (!$entity) {
            $entity = new $this->entity['class']();

            try {
                $this->em->persist($entity);
                $this->em->flush();
            } catch (OptimisticLockException | ORMException $exception) {
                // redirect to admin's default entity when section creation failed
                return $this->redirectToRoute('admin');
            }
        }

        $this->request->query->set('id', $entity->getId());

        $this->request->attributes->set(
            'easyadmin',
            array_merge($this->request->attributes->get('easyadmin'), ['item' => $entity])
        );

        return parent::editAction();
    }
}