Symfony 7.4 DependencyInjection Component

GitHub: https://github.com/symfony/dependency-injection Docs: https://symfony.com/doc/7.4/components/dependency_injection.html

Quick Reference

Basic Service Registration

php

use Symfony\Component\DependencyInjection\ContainerBuilder;

$container = new ContainerBuilder();
$container->setParameter('mailer.transport', 'sendmail');
$container
    ->register('mailer', Mailer::class)
    ->addArgument('%mailer.transport%');

Injecting Service References

php

use Symfony\Component\DependencyInjection\Reference;

$container
    ->register('newsletter_manager', NewsletterManager::class)
    ->addArgument(new Reference('mailer'));

Setter Injection

php

$container
    ->register('newsletter_manager', NewsletterManager::class)
    ->addMethodCall('setMailer', [new Reference('mailer')]);

PHP Configuration (services.php)

php

namespace Symfony\Component\DependencyInjection\Loader\Configurator;

return static function (ContainerConfigurator $container): void {
    $services = $container->services();

    $services->defaults()
        ->autowire()
        ->autoconfigure();

    $services->load('App\\', '../src/')
        ->exclude('../src/{DependencyInjection,Entity,Kernel.php}');

    $services->set('mailer', Mailer::class)
        ->args([param('mailer.transport')]);
};

YAML Configuration (services.yaml)

yaml

services:
    _defaults:
        autowire: true
        autoconfigure: true

    App\:
        resource: '../src/'
        exclude: '../src/{DependencyInjection,Entity,Kernel.php}'

    mailer:
        class: Mailer
        arguments: ['%mailer.transport%']

    newsletter_manager:
        class: NewsletterManager
        calls:
            - [setMailer, ['@mailer']]

Loading Configuration Files

php

use Symfony\Component\Config\FileLocator;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Loader\YamlFileLoader;

$container = new ContainerBuilder();
$loader = new YamlFileLoader($container, new FileLocator(__DIR__));
$loader->load('services.yaml');

Handling Missing Services

php

use Symfony\Component\DependencyInjection\ContainerInterface;

// Available behaviors for missing references:
ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE;         // throws at compile (default)
ContainerInterface::RUNTIME_EXCEPTION_ON_INVALID_REFERENCE;  // throws at runtime
ContainerInterface::NULL_ON_INVALID_REFERENCE;               // returns null
ContainerInterface::IGNORE_ON_INVALID_REFERENCE;             // ignores wrapping call
ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE;       // ignores uninitialized

Full Documentation

For complete details including compiler passes, service tags, service decoration, lazy services, autowiring configuration, factory services, parent services, immutable setters, and all configuration formats, see references/dependency-injection.md.