DemoController.php

<?php

namespace AppBundle\Controller;

use AppBundle\Entity\Author;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;

class DefaultController extends Controller
{
    /**
     * @Route("/", name="homepage")
     */
    public function indexAction()
    {
        $em = $this->getDoctrine()->getManager();

        $authors = $em->getRepository('AppBundle:Author')->findAll();

        return $this->render('default/index.html.twig', ['authors' => $authors]);
    }

    /**
     * @Route("/fill", name="fill")
     */
    public function fillAction()
    {
        $em = $this->getDoctrine()->getManager();
        $count = $em->getRepository(Author::class)->selectCountAuthors();
        $count++;

        $author = new Author();
        $author->setFirstName('Author');
        $author->setLastName('First' . $count);
        $author->setUsername('a' . $count);
        $author->setBirthday(new \DateTime());
        $em->persist($author);
        $em->flush();

        return $this->redirectToRoute('homepage');
    }
}