How to Impersonate a User ¶

// src/Service/SomeService.php
namespace App\Service;

use Symfony\Bundle\SecurityBundle\Security;
use Symfony\Component\Security\Core\Authentication\Token\SwitchUserToken;
// ...

class SomeService
{
    private $security;

    public function __construct(Security $security)
    {
        $this->security = $security;
    }

    public function someMethod()
    {
        // ...

        $token = $this->security->getToken();

        if ($token instanceof SwitchUserToken) {
            $impersonatorUser = $token->getOriginalToken()->getUser();
        }

        // ...
    }
}

// src/Security/Voter/SwitchToCustomerVoter.php
namespace App\Security\Voter;

use Symfony\Bundle\SecurityBundle\Security;
use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
use Symfony\Component\Security\Core\Authorization\Voter\Voter;
use Symfony\Component\Security\Core\User\UserInterface;

class SwitchToCustomerVoter extends Voter
{
    private $security;

    public function __construct(Security $security)
    {
        $this->security = $security;
    }

    protected function supports($attribute, $subject): bool
    {
        return in_array($attribute, ['CAN_SWITCH_USER'])
            && $subject instanceof UserInterface;
    }

    protected function voteOnAttribute($attribute, $subject, TokenInterface $token): bool
    {
        $user = $token->getUser();
        // if the user is anonymous or if the subject is not a user, do not grant access
        if (!$user instanceof UserInterface || !$subject instanceof UserInterface) {
            return false;
        }

        // you can still check for ROLE_ALLOWED_TO_SWITCH
        if ($this->security->isGranted('ROLE_ALLOWED_TO_SWITCH')) {
            return true;
        }

        // check for any roles you want
        if ($this->security->isGranted('ROLE_TECH_SUPPORT')) {
            return true;
        }

        /*
         * or use some custom data from your User object
        if ($user->isAllowedToSwitch()) {
            return true;
        }
        */

        return false;
    }
}

// src/EventListener/SwitchUserSubscriber.php
namespace App\EventListener;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Security\Http\Event\SwitchUserEvent;
use Symfony\Component\Security\Http\SecurityEvents;

class SwitchUserSubscriber implements EventSubscriberInterface
{
    public function onSwitchUser(SwitchUserEvent $event): void
    {
        $request = $event->getRequest();

        if ($request->hasSession() && ($session = $request->getSession())) {
            $session->set(
                '_locale',
                // assuming your User has some getLocale() method
                $event->getTargetUser()->getLocale()
            );
        }
    }

    public static function getSubscribedEvents(): array
    {
        return [
            // constant for security.switch_user
            SecurityEvents::SWITCH_USER => 'onSwitchUser',
        ];
    }
}