مشروع: طبقة Spring Data JPA كاملة

// Customer.java package com.example.shop.domain; import jakarta.persistence.*; import org.springframework.data.annotation.CreatedDate; import org.springframework.data.annotation.LastModifiedDate; import org.springframework.data.jpa.domain.support.AuditingEntityListener; import java.time.Instant; import java.util.ArrayList; import java.util.List; @Entity @Table(name = "customers") @EntityListeners(AuditingEntityListener.class) public class Customer { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @Column(nullable = false, length = 100) private String name; @Column(nullable = false, unique = true, length = 150) private String email; @OneToMany(mappedBy = "customer", cascade = CascadeType.ALL, orphanRemoval = true) private List<Order> orders = new ArrayList<>(); @CreatedDate @Column(updatable = false) private Instant createdAt; @LastModifiedDate private Instant updatedAt; // الـ getters/setters المعيارية محذوفة للإيجاز }

// Order.java @Entity @Table(name = "orders") @EntityListeners(AuditingEntityListener.class) public class Order { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @ManyToOne(fetch = FetchType.LAZY, optional = false) @JoinColumn(name = "customer_id") private Customer customer; @Enumerated(EnumType.STRING) @Column(nullable = false, length = 20) private OrderStatus status; @OneToMany(mappedBy = "order", cascade = CascadeType.ALL, orphanRemoval = true) private List<OrderItem> items = new ArrayList<>(); @CreatedDate @Column(updatable = false) private Instant placedAt; @LastModifiedDate private Instant updatedAt; }

// CustomerRepository.java package com.example.shop.repository; import com.example.shop.domain.Customer; import com.example.shop.dto.CustomerSummary; import org.springframework.data.domain.Page; import org.springframework.data.domain.Pageable; import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.data.jpa.repository.Query; import org.springframework.data.repository.query.Param; import java.util.Optional; public interface CustomerRepository extends JpaRepository<Customer, Long> { Optional<Customer> findByEmail(String email); boolean existsByEmail(String email); // استعلام مبني على إسقاط — يجلب id + name + email فقط من قاعدة البيانات Page<CustomerSummary> findBy(Pageable pageable); // جلب العميل مع جميع طلباته في استعلام واحد (يتجنّب مشكلة N+1) @Query("SELECT c FROM Customer c LEFT JOIN FETCH c.orders WHERE c.id = :id") Optional<Customer> findByIdWithOrders(@Param("id") Long id); }

// CustomerSummary.java (واجهة إسقاط مغلقة) package com.example.shop.dto; public interface CustomerSummary { Long getId(); String getName(); String getEmail(); }

// OrderRepository.java package com.example.shop.repository; import com.example.shop.domain.Order; import com.example.shop.domain.OrderStatus; import org.springframework.data.domain.Page; import org.springframework.data.domain.Pageable; import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.data.jpa.repository.Modifying; import org.springframework.data.jpa.repository.Query; import org.springframework.data.repository.query.Param; import java.time.Instant; import java.util.List; public interface OrderRepository extends JpaRepository<Order, Long> { // مشتق: جميع طلبات عميل مُرتَّبة من الأحدث للأقدم List<Order> findByCustomerIdOrderByPlacedAtDesc(Long customerId); // طلبات مُرقَّمة حسب الحالة Page<Order> findByStatus(OrderStatus status, Pageable pageable); // استعلام JPQL تجميعي @Query("SELECT COUNT(o) FROM Order o WHERE o.customer.id = :customerId AND o.status = :status") long countByCustomerAndStatus(@Param("customerId") Long customerId, @Param("status") OrderStatus status); // تحديث جماعي للحالة باستخدام استعلام تعديلي — يتجنّب تحميل الكيانات في الذاكرة @Modifying @Query("UPDATE Order o SET o.status = :newStatus WHERE o.status = :oldStatus AND o.placedAt < :before") int cancelStaleDraftOrders(@Param("oldStatus") OrderStatus oldStatus, @Param("newStatus") OrderStatus newStatus, @Param("before") Instant before); }

// OrderService.java package com.example.shop.service; import com.example.shop.domain.*; import com.example.shop.repository.*; import jakarta.persistence.EntityNotFoundException; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Transactional; import java.util.List; @Service @Transactional(readOnly = true) // افتراضي: كل الطوابع للقراءة فقط public class OrderService { private final OrderRepository orderRepository; private final CustomerRepository customerRepository; private final ProductRepository productRepository; public OrderService(OrderRepository orderRepository, CustomerRepository customerRepository, ProductRepository productRepository) { this.orderRepository = orderRepository; this.customerRepository = customerRepository; this.productRepository = productRepository; } public Order findById(Long id) { return orderRepository.findById(id) .orElseThrow(() -> new EntityNotFoundException("Order " + id + " not found")); } @Transactional // يتجاوز readOnly=true على مستوى الفئة — هذه الطريقة تكتب public Order placeOrder(Long customerId, List<OrderLineRequest> lines) { Customer customer = customerRepository.findById(customerId) .orElseThrow(() -> new EntityNotFoundException("Customer not found")); Order order = new Order(); order.setCustomer(customer); order.setStatus(OrderStatus.PENDING); for (OrderLineRequest line : lines) { Product product = productRepository.findById(line.productId()) .orElseThrow(() -> new EntityNotFoundException("Product not found")); OrderItem item = new OrderItem(); item.setOrder(order); item.setProduct(product); item.setQuantity(line.quantity()); item.setUnitPrice(product.getPrice()); order.getItems().add(item); } return orderRepository.save(order); // Hibernate يُدرج Order وجميع OrderItems في معاملة واحدة } }

@SpringBootApplication @EnableJpaAuditing public class ShopApplication { public static void main(String[] args) { SpringApplication.run(ShopApplication.class, args); } }

@DataJpaTest class OrderRepositoryTest { @Autowired private OrderRepository orderRepository; @Autowired private CustomerRepository customerRepository; @Test void findByCustomerId_returnsMostRecentFirst() { Customer c = new Customer(); c.setName("Alice"); c.setEmail("alice@example.com"); customerRepository.save(c); Order o1 = new Order(); o1.setCustomer(c); o1.setStatus(OrderStatus.PENDING); orderRepository.save(o1); Order o2 = new Order(); o2.setCustomer(c); o2.setStatus(OrderStatus.COMPLETED); orderRepository.save(o2); List<Order> results = orderRepository .findByCustomerIdOrderByPlacedAtDesc(c.getId()); assertThat(results).hasSize(2); assertThat(results.get(0).getStatus()).isEqualTo(OrderStatus.COMPLETED); } }