Hibernate在外键字段中插入空值 [英] Hibernate is inserting null values in foreign key field

问题描述

我有2个简单的域对象，如下所示..使用MYSQL DB.

I have 2 simple domain objects as follows..with MYSQL DB.

@Entity
@Table(name="Product")
public class Product {
    @Id
    @Column(name="productId")
    @GeneratedValue
    protected int productId;
    @Column(name="Product_Name")
    protected String name;
    @OneToMany(cascade = javax.persistence.CascadeType.ALL,mappedBy="product")
    protected List<ProductOption> productoption = new ArrayList<ProductOption>();

和第二个对象

@Entity
@Table(name="ProductOption")
public class ProductOption{


    /**
     * 
     */

    @Id
    @Column(name="product_option_id")
    @GeneratedValue
    protected int productOptionId;


    //@JoinColumn(name="productId")
    @ManyToOne()
    protected Product product;      

    @Column(name="ProductTopping")
    private String topping;

和我的主要方法.

public class Createschema {

    public static void main(String[] args) {

        Product product = new Product();
        product.setName("Coffee");

        ProductOption po2 = new ProductOption();
        po2.setTopping("barbeque");
        ProductOption po = new ProductOption();
        po.setTopping("whipcream");
        ProductOption po1 = new ProductOption();
        po1.setTopping("honeymustard");


        List<ProductOption> productoptions = new ArrayList<ProductOption>();

        productoptions.add(po1);
        productoptions.add(po2);
        productoptions.add(po);



        System.out.println("schema!");
        Configuration configuration = new Configuration().configure();

        StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties());

        SessionFactory factory = configuration.buildSessionFactory(builder.build());

        Session session = factory.openSession();
        session.beginTransaction();
        product.setProductoption(productoptions);
        session.save(product);
        session.getTransaction().commit();
        session.close();
        System.out.println(product.getName());

        for(int i=0;i<product.getProductoption().size();i++){
        System.out.println(product.getProductOptionsAsListOfStrings().get(i));  
        System.out.println(product.getProductoption().get(i).getTopping());
        }

    }

}

出于某种原因，hibernate在productoptions的外键字段中插入了空值. 我尝试更改级联样式，生成策略，但没有任何效果.使nullable = false引发error.插入了数据，但在productoptions表中，foreign键字段为null. 请帮助

For some reason hibernate is inserting null values in foreign key field of productoptions. I tried changing cascading styles, generation strategies, but nothing worked. Making nullable=false throws error . Data gets inserted but in the productoptions table foriegn key field is null. Please help

推荐答案

在Product更改中

@OneToMany(mappedBy="product")
List<ProductOption> productoption;

在ProductOption更改中

@ManyToOne
@JoinColumn(name="productId")
private Product product;

最后是Createschema

session.beginTransaction();

Product product = new Product();
product.setName("Coffee");
session.save(product);

ProductOption po2 = new ProductOption();
po2.setTopping("barbeque");
po2.setProduct(product)
ProductOption po = new ProductOption();
po.setTopping("whipcream");
po2.setProduct(product)
ProductOption po1 = new ProductOption();
po1.setTopping("honeymustard");
po2.setProduct(product)

session.save(po2);
session.save(po);
session.save(po1);

session.getTransaction().commit();
session.close();

这篇关于Hibernate在外键字段中插入空值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！