Domain-Driven Design (DDD) helps developers model complex business domains clearly, aligning code structure with business logic.

Core Concepts

  • Entities: Objects with identity
  • Value Objects: Immutable objects
  • Aggregates: Groups of related entities
  • Repositories: Access to aggregates
  • Services: Business logic that doesn’t belong to an entity

Example: Order Aggregate

class Order {
    private array $items = [];
    public function addItem(Product $product, int $quantity) {
        $this->items[] = new OrderItem($product, $quantity);
    }
}

Repositories

Repositories abstract storage:

interface OrderRepository {
    public function save(Order $order): void;
    public function findById(int $id): ?Order;
}

Benefits

  • Clear separation of domain logic
  • Improved maintainability
  • Facilitates testing

Conclusion

Implementing DDD in PHP projects improves structure and makes scaling applications easier.