عرض عملي: بناء ميزة المنتجات طبقة بطبقة

خطوة بخطوة

1. Create the Product domain class and ProductRepository interface.
2. Implement InMemoryProductRepository with a Map and sample data.
3. Write ProductService with list() and get(id).
4. Planned mistake: put the "not found" decision and a price calculation in the controller. Fix: move both into the service; the controller only delegates.
5. Write ProductController, run the app, and call both endpoints with curl.