如何在 Spring Boot 中获取添加订单的选定项目？

Question

I have three entities user, item, order. ORDER entity has ManyToMany association with item and ManyToOne with user.

1.Item Entity

@Entity
public class Item {
Integer id;
String name;
String category;

@ManyToMany
Order order;

}

2.User Entity

@Entity
public class user {
Integer id;
String username;
String email;

@OneToMany
Order order;

}

3.order Entity

@Entity
public class order {
Integer id;
Integer price;
Integer quantity;
String address;
Integer p_number;

@ManyToOne
Use user;

@ManyToMany
Item item;

}

I've problem with adding an order, I don't know how to get selected items in orderService class for addOrder method?

OrderServiceImpl.java

@Service
public class OrderServiceImpl implements OrderService {

    @Autowired
    OrderRepo orderRepo;

    public Order addOrder (Order order) {
        return orderRepo.save(order);
    }

}

Answer 1

In mapping, the fields representing many side have to be either list or set

In user entity

@OneToMany(mappedBy="user")
List<Order> orders;

In item entity

@ManyToMany
List<Order> orders;

In order entity

@ManyToOne
Use user;

@ManyToMany
List<Item> items;