如何使用 jpa 从数据库中删除单向、一对一映射

Question

我想从数据库中删除商家表中的行和地址表中的行。商户的表中有address_id。我已经为 Merchant 和 Address 创建了 DAO。如何仅使用实体管理器来做到这一点？我省略了导入、getter 和 setter。似乎只删除了Merchant表中的行，而保留了地址表中的行。任何帮助将不胜感激，谢谢。每当我删除商家实体时，它都会保留地址id，并且不会删除Address表中相应的地址。我不明白为什么。@Entitypublic class Merchant {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private int id;    private String name;    @OneToOne    private Address address;    public Merchant() {    }}public class MerchantDAO {    protected static EntityManagerFactory emf = Persistence.createEntityManagerFactory("hamzaspersistenceunit");    public void persist(Merchant merchant) {        EntityManager em = emf.createEntityManager();        em.getTransaction().begin();        em.persist(merchant);        em.getTransaction().commit();        em.close();    }    public void removeMerchant(Merchant merchant) {        EntityManager em = emf.createEntityManager();        em.getTransaction().begin();        em.remove(em.contains(merchant) ? merchant : em.merge(merchant));        em.getTransaction().commit();        em.close();    }}@Entitypublic class Address {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private int id;    private String name;    private String streetAddress;    private String city;    private String state;    private String zipCode;    public Address(String name, String streetAddress, String city, String state, String zipCode) {        super();        this.name = name;        this.streetAddress = streetAddress;        this.city = city;        this.state = state;        this.zipCode = zipCode;    }}public class AddressDAO {    protected static EntityManagerFactory emf = Persistence.createEntityManagerFactory("hamzaspersistenceunit");    public AddressDAO() {    }    public void persist(Address address) {        EntityManager em = emf.createEntityManager();        em.getTransaction().begin();        em.persist(address);        em.getTransaction().commit();        em.close();    }

Answer 1

尝试使用 注释实体address中的字段。默认情况下，此选项设置为，因此删除操作不会级联到实体。Merchant@OneToOne(orphanRemoval = true)falseAddress

更新：此问题的正确解决方案是使用@OneToOne(cascade = CascadeType.REMOVE)