base.html.twig

<div class="page-wrapper">
      {% if app.flashes %}
      <div class="container">
        {% for label, messages in app.flashes %}

             {% for message in messages %}

                 <div class="alert alert-{{ label }} alert-dismissible fade show" role="alert">

                     <button type="button" class="close" data-dismiss="alert" aria-label="Close">

                         <span aria-hidden="true">&times;</span>

                     </button>

                     {{ message }}

                 </div>

             {% endfor %}

         {% endfor %}
      </div>
    {% endif %}
      <div class="background"></div>
      {% block body %}{% endblock %}
    </div>

securityController.php

<?php

namespace App\Controller;

use \DateTime;

use Symfony\Component\Routing\Annotation\Route;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Security\Http\Authentication\AuthenticationUtils;
use Symfony\Component\Security\Core\Encoder\UserPasswordEncoderInterface;

use Symfony\Bundle\FrameworkBundle\Controller\Controller;

use App\Form\UtilisateurLoginType;
use App\Form\UtilisateurSignupType;
use App\Entity\Utilisateur;
use App\DTO\UtilisateurSignupData;

use App\Entity\Entreprise;

class SecurityController extends Controller
{
    /**
     * @Route("/login", name="login")
     */
    public function login(Request $request, AuthenticationUtils $authenticationUtils)
    {
        $session = $this->get('session');

        if($session->get('_security.main.target_path')) {
            /*$this->addFlash('error', 'Vous devez être authentifié pour continuer');
            return $this->redirectToRoute('homepage');*/
        }

        // get the login error if there is one
	    $error = $authenticationUtils->getLastAuthenticationError();

	    // last username entered by the user
	    $lastUsername = $authenticationUtils->getLastUsername();

	    // Build form
	    // If the username exists
	    if ($lastUsername) {
	    	$opt = ['_username' => $lastUsername];
	    } else {
	    	$opt = [];
	    }

	    $form = $this->createForm(UtilisateurLoginType::class, $opt);

	    return $this->render('security/login.html.twig', array(
	        'form'          => $form->createView(),
	        'error'         => $error,
	        'titre'         => 'Login',
	    ));
    }

    /**
     * @Route("/signup", name="signup")
     */
    public function signup(Request $request, UserPasswordEncoderInterface $passwordEncoder)
    {

    	// Repository to check emails and usernames
    	$repository = $this->getDoctrine()->getRepository(Utilisateur::class);

    	// Build form with data
        $utilisateurData = new UtilisateurSignupData($repository);

        $form = $this->createForm(UtilisateurSignupType::class, $utilisateurData);

        // Handle form request if exists
        $form->handleRequest($request);

	    if ($form->isSubmitted() && $form->isValid()) {

	    	// Using DTO
            $utilisateur = new Utilisateur();
            $utilisateur->setEmail($utilisateurData->getEmail());
            $utilisateur->setUsername($utilisateurData->getUsername());
            $utilisateur->setPassword($utilisateurData->getPassword());

	    	// Encode password
	    	$password = $passwordEncoder->encodePassword($utilisateur, $utilisateur->getPassword());

	    	$utilisateur->setPassword($password);

            // Saving !
            $entityManager = $this->getDoctrine()->getManager();
            $entityManager->persist($utilisateur);
            $entityManager->flush();

            $this->addFlash('success', 'Inscrit avec succès ! Vous pouvez désormais vous connecter '.$utilisateur->getUsername());

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

        return $this->render('security/signup.html.twig', array(
        	'form' => $form->createView(),
        	'titre' => 'Inscription',
        ));
    }
}