SOLID Principles in Laravel: A Practical Guide

After years working with Laravel, I can say the difference between a project that scales and one that becomes a headache lies in how we apply fundamental design principles.

Single Responsibility

Every class should have one reason to change. In Laravel, this means pulling business logic out of controllers:

// ❌ Controller doing everything
class OrderController extends Controller
{
    public function store(Request $request)
    {
        // validation, business logic, notifications...
    }
}

// ✅ Separate responsibilities
class OrderController extends Controller
{
    public function store(
        StoreOrderRequest $request,
        CreateOrderAction $action
    ) {
        return $action->execute($request->validated());
    }
}

Dependency Inversion

Laravel’s Service Container is perfect for this. Program against interfaces, not implementations:

// Interface
interface PaymentGateway
{
    public function charge(Money $amount): PaymentResult;
}

// Binding
$this->app->bind(PaymentGateway::class, StripeGateway::class);

These principles aren’t academic — they’re the difference between delivering software that works and software that lasts.

Want to dive deeper into any of these? Let me know on LinkedIn!