feat: Implement order items entity and database migration

- Introduce OrderItems entity with persistence capabilities.
- Establish a one-to-many relationship between Orders and OrderItems.
- Update Orders entity to reflect the relationship change.
- Create a Flyway migration script to create the order_items table and drop the jsonb items column from the orders table.

src/main/java/com/vegamarket/orderservice/dtos/OrderItems.java

@@ -1,9 +1,13 @@
 package com.vegamarket.orderservice.dtos;
 
+import com.vegamarket.orderservice.model.Orders;
+import jakarta.persistence.*;
 import lombok.*;
 
 import java.math.BigDecimal;
 
+@Entity
+@Table(name = "order_items")
 @Getter
 @Setter
 @AllArgsConstructor
@@ -11,6 +15,15 @@ import java.math.BigDecimal;
 @Builder
 public class OrderItems {
 
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long orderItemId;
+    private Long productId;
+    private Long quantity;
+
+    @ManyToOne(fetch = FetchType.LAZY, optional = false)
+    @JoinColumn(name = "order_id", nullable = false)
+    private Orders order;
     private String name;
     private BigDecimal price;
 }

src/main/java/com/vegamarket/orderservice/model/Orders.java

@@ -34,8 +34,11 @@ public class Orders {
     private BigDecimal totalAmount;
     private String traceId;
 
-    @Column(columnDefinition = "jsonb", nullable = false)
-    @JdbcTypeCode(SqlTypes.JSON)
+    @OneToMany(
+        mappedBy = "order",
+            cascade = CascadeType.ALL,
+            orphanRemoval = true
+    )
     private List<OrderItems> items;
 
     @CreationTimestamp

src/main/resources/db/migration/V2__CREATE-ORDERS-ITEMS-TABLE.sql

@@ -0,0 +1,15 @@
+alter table orders
+drop column items;
+
+create table order_items (
+    order_item_id bigint generated always as identity primary key,
+    productId bigint not null,
+    quantity int not null,
+    order_id bigint not null,
+    name varchar(255) not null,
+    price numeric(19,2) not null,
+    constraint fk_order_item_order
+        foreign key (order_id)
+        references orders(order_id)
+        on delete cascade
+);