为什么在父实体中创建 Spring Boot 列表中的列表 id 为空？

Question

我在订单项中遇到问题

order_id

它为空，因为我在订单中创建

OrderItems

，就像订单的 JSON

{
 "supplier": {
    "supplierId": 1,
    "supplierName": "yahya",
    "country": "Algeria",
    "region": "undefined",
    "productIds": [142, 141]
  },
  "orderItems": [
    {
      "productId": 1,
      "quantity": 2,
      "order_price": 10
    },
    {
      "productId": 2,
      "quantity": 1,
      "order_price": 15
    }
  ],
  "orderType": "IMPORT",
  "orderDate": "2024-05-10",
  "reference": "ABC123",
  "total_price": 35
}

package com.example.importexportservice.models;
import jakarta.persistence.*;
@Entity
@Table(name = "order_item")
public class OrderItem {


    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "order_item_id")
    private Long id;

    @ManyToOne
    @JoinColumn(name = "order_id")
    private Order order;

    @Column(name = "product_id")
    private Long productId;

    @Column(name = "quantity")
    private int quantity;
    @Column(name = "Order_price")
    private int Order_price;

    public OrderItem() {
    }


    public OrderItem(Long id, Order order, Long productId, int quantity, int order_price) {
        this.id = id;
        this.order = order;
        this.productId = productId;
        this.quantity = quantity;
        this.Order_price = order_price;
    }


} 

package com.example.importexportservice.models;

import jakarta.persistence.*;


import java.util.Date;
import java.util.List;

@Entity
@Table(name = "order_table")
public class Order {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "order_id")
    private Long orderId;


    @ManyToOne
    @JoinColumn(name = "supplier_id")
    private Supplier supplier;


    @OneToMany(mappedBy = "order", cascade = CascadeType.ALL ,fetch = FetchType.EAGER)
    private List<OrderItem> orderItems;

    public List<OrderItem> getOrderItems() {
        return orderItems;
    }

    public void setOrderItems(List<OrderItem> orderItems) {
        this.orderItems = orderItems;
    }

    @Enumerated(EnumType.STRING)
    @Column(name = "order_Type")
    private OrderType orderType;

    public Order(Long orderId, Supplier supplier, List<OrderItem> orderItems, OrderType orderType, Date orderDate, String reference, int total_price) {
        this.orderId = orderId;
        this.supplier = supplier;
        this.orderItems= orderItems;
        this.orderType = orderType;
        this.orderDate = orderDate;
        this.reference = reference;
        Total_price = total_price;
    }

    @Temporal(TemporalType.DATE)
    @Column(name = "order_date")
    private Date orderDate;




    @Column(name = "order_reference")
    private String reference;

    @Column(name = "order_Total_price")
    private int Total_price;

    public Order() {
    }


}

所以我在 orderitem 中发现订单 id 为空，即使我尝试在构造函数中循环列表并影响订单 id，但我仍然发现它为空。是我的映射错误还是我可以做其他事情？

Answer 1

我们可以通过多种方式解决这个问题。在这里我解释其中 1 个。

您必须在 Order 和 OrderItem POJO 类中进行更改。 从 OrderItem 中删除

 private Order order;

，然后在 Order 中只需将

@OneToMany

注释替换为

@OneToMany(cascade = CascadeType.ALL)
@JoinColumn(name = "order_id", referencedColumnName = "order_id")

你也可以参考这个Gist