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Symfony 6 and Drupal 11: How the Upgrade Will Impact Developers

With Drupal 11 aligning itself closely with Symfony 6, developers are facing a significant shift in architecture, practices, and performance expectations. Since Symfony is the foundational PHP framework that powers Drupal, every major Symfony release introduces ripple effects across the Drupal ecosystem.

This article explores how Symfony 6's integration into Drupal 11 will impact developers—highlighting performance, modernization, and necessary refactoring.

🔹 Why Symfony Matters in Drupal

Drupal relies on Symfony for its routing, HTTP handling, services, dependency injection, and more. When Drupal upgrades its Symfony version, developers must adapt to the new patterns and deprecations introduced by Symfony.

🔹 Key Impacts of Symfony 6 in Drupal 11

1. Dropped Legacy Code and Deprecated Features

Symfony 6 removes all features deprecated in Symfony 5.4. That means:

  • Deprecated controllers and helper methods in contrib/custom modules will break.

  • You’ll need to refactor event listeners and use modern service definitions.

✅ Example: The ContainerAwareCommand is removed in Symfony 6. Use Command with Dependency Injection instead.

// ❌ Old Symfony 5-style command (deprecated)
use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;

class MyOldCommand extends ContainerAwareCommand {
    protected function execute(InputInterface $input, OutputInterface $output) {
        $logger = $this->getContainer()->get('logger');
        $logger->info('Running legacy command.');
    }
}

// ✅ New Symfony 6-compatible command
use Symfony\Component\Console\Command\Command;
use Psr\Log\LoggerInterface;

class MyNewCommand extends Command {
    private LoggerInterface $logger;

    public function __construct(LoggerInterface $logger) {
        parent::__construct();
        $this->logger = $logger;
    }

    protected function execute(InputInterface $input, OutputInterface $output): int {
        $this->logger->info('Running modern command.');
        return Command::SUCCESS;
    }
}

2. Typed Properties and Strict Types

Symfony 6 and Drupal 11 enforce modern PHP 8+ practices, including:

  • Typed class properties

  • Constructor property promotion

  • Strict return types

// Before: Loose typing
private $node;

// After: Strong typing in Symfony 6
private NodeInterface $node;

3. Event System Modernization

Symfony’s EventDispatcher has evolved:

  • Legacy event names are removed

  • Event classes now use typed listeners and final classes

Update your custom event subscribers accordingly:

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpKernel\Event\RequestEvent;

class CustomSubscriber implements EventSubscriberInterface {
    public static function getSubscribedEvents(): array {
        return [
            RequestEvent::class => 'onRequest',
        ];
    }

    public function onRequest(RequestEvent $event): void {
        // Handle the request event
    }
}

4. Service Configuration Using Attributes

Symfony 6 supports PHP 8 attributes for service configuration. Drupal may gradually adopt this for service definitions.

use Symfony\Contracts\Service\Attribute\Required;

class SomeService {
    #[Required]
    public function setLogger(LoggerInterface $logger): void {
        $this->logger = $logger;
    }
}

🔹 How Developers Should Prepare

  1. Audit Custom Code: Use static analysis tools like PHPStan or Drupal Rector to identify deprecated patterns.

  2. Use Dependency Injection Properly: Avoid using \Drupal::service() in new code.

  3. Contrib Module Maintainers: Ensure compatibility by testing with Symfony 6 in advance.

  4. Follow Symfony Best Practices: Study Symfony 6 documentation to adopt idiomatic usage.

🔹 Conclusion

The integration of Symfony 6 into Drupal 11 represents more than a version bump — it's a leap toward modern, secure, and high-performance PHP. While it introduces breaking changes, it also brings cleaner APIs, faster execution, and better developer ergonomics.

Drupal developers who embrace these changes will not only write better code—they’ll build future-ready applications that align with the broader PHP ecosystem.

Tags
Drupal 11