Laravel Service Container

The service container is a powerful tool for managing class dependencies and performing dependency injection.

Binding Basics

// Simple binding
$this->app->bind(PaymentGateway::class, function ($app) {
    return new StripeGateway(config('services.stripe.key'));
});
// Binding interfaces to implementations
$this->app->bind(
    PaymentGatewayInterface::class,
    StripeGateway::class
);
// Singleton binding
$this->app->singleton(Cache::class, function ($app) {
    return new RedisCache($app['config']['cache.redis']);
});

Automatic Resolution

Laravel can automatically resolve classes without explicit bindings when dependencies can be determined from type hints:

class UserController extends Controller
{
    public function __construct(
        private UserRepository $users,
        private PaymentGateway $payments
    ) {}
    public function show(User $user)
    {
        // Laravel automatically injects dependencies
    }
}

Contextual Binding

$this->app->when(PhotoController::class)
    ->needs(Filesystem::class)
    ->give(function () {
        return Storage::disk('photos');
    });
$this->app->when(VideoController::class)
    ->needs(Filesystem::class)
    ->give(function () {
        return Storage::disk('videos');
    });

Service Providers

class PaymentServiceProvider extends ServiceProvider
{
    public function register()
    {
        $this->app->singleton(PaymentGateway::class, function () {
            return new StripeGateway(
                config('services.stripe.key'),
                config('services.stripe.secret')
            );
        });
    }
    public function boot()
    {
        // Run after all providers are registered
    }
}