Hibernate JPA级联删除问题

Question

为了解释我的问题，我创建了这个简单的项目，其中包含两个表：item 和 order1（item 具有 orderId 作为外键）。

现在，当我尝试从订单表中删除一行时，我收到错误消息，指出特定订单 ID 与“项目”表中的少数项目相关联。

所以，我要做的是遍历所有项目对象（使用“急切”加载），并为每个对象调用 destroy()。在删除所有项目后，我调用 order.destroy()。 但是现在，我收到以下错误：

Exception in thread "main" javax.persistence.RollbackException: Error while commiting the transaction
        at org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:71)
        at     com.sourind.test.testorm.controller.ItemJpaController.destroy(ItemJpaController.java:112)
        at com.sourind.test.testorm.App.main(App.java:31)
Caused by: org.hibernate.ObjectDeletedException: deleted entity passed to persist:     [com.sourind.test.testorm.entity.Item#<null>]

我正在使用休眠（JPA 2.0）。非常感谢您对此事的任何帮助。

作为参考，我复制了netbeans创建的实体类：

@Entity
@Table(name = "item", catalog = "test", schema = "")
@NamedQueries({
@NamedQuery(name = "Item.findAll", query = "SELECT i FROM Item i"),
@NamedQuery(name = "Item.findById", query = "SELECT i FROM Item i WHERE i.id = :id"),
@NamedQuery(name = "Item.findByName", query = "SELECT i FROM Item i WHERE i.name = :name")})
public class Item implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;
    @Basic(optional = false)
    @Column(name = "name")
    private String name;
    @JoinColumn(name = "orderId", referencedColumnName = "id")
    @ManyToOne(optional = false)
    private Order1 order1;

    public Item() {
    }

    public Item(Integer id) {
       this.id = id;
    }

public Item(Integer id, String name) {
    this.id = id;
    this.name = name;
}

public Integer getId() {
    return id;
}

public void setId(Integer id) {
    this.id = id;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public Order1 getOrder1() {
    return order1;
}

public void setOrder1(Order1 order1) {
    this.order1 = order1;
}

@Override
public int hashCode() {
    int hash = 0;
    hash += (id != null ? id.hashCode() : 0);
    return hash;
}

@Override
public boolean equals(Object object) {
    // TODO: Warning - this method won't work in the case the id fields are not set
    if (!(object instanceof Item)) {
        return false;
    }
    Item other = (Item) object;
    if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
        return false;
    }
    return true;
}

@Override
public String toString() {
    return "com.sourind.test.testorm.entity.Item[id=" + id + "]";
}

}

还有 order1 类：

@Entity
@Table(name = "order", catalog = "test", schema = "")
@NamedQueries({
    @NamedQuery(name = "Order1.findAll", query = "SELECT o FROM Order1 o"),
    @NamedQuery(name = "Order1.findById", query = "SELECT o FROM Order1 o WHERE o.id = :id"),
    @NamedQuery(name = "Order1.findByOrderDate", query = "SELECT o FROM Order1 o WHERE o.orderDate = :orderDate")})
public class Order1 implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;
    @Basic(optional = false)
    @Column(name = "orderDate")
    @Temporal(TemporalType.TIMESTAMP)
private Date orderDate;
@OneToMany(cascade = CascadeType.ALL, mappedBy = "order1", fetch=FetchType.EAGER)
private List<Item> itemList;

public Order1() {
}

public Order1(Integer id) {
    this.id = id;
}

public Order1(Integer id, Date orderDate) {
    this.id = id;
    this.orderDate = orderDate;
}

public Integer getId() {
    return id;
}

public void setId(Integer id) {
    this.id = id;
}

public Date getOrderDate() {
    return orderDate;
}

public void setOrderDate(Date orderDate) {
    this.orderDate = orderDate;
}

public List<Item> getItemList() {
    return itemList;
}

public void setItemList(List<Item> itemList) {
    this.itemList = itemList;
}

@Override
public int hashCode() {
    int hash = 0;
    hash += (id != null ? id.hashCode() : 0);
    return hash;
}

@Override
public boolean equals(Object object) {
    // TODO: Warning - this method won't work in the case the id fields are not set
    if (!(object instanceof Order1)) {
        return false;
    }
    Order1 other = (Order1) object;
    if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
        return false;
    }
    return true;
}

@Override
public String toString() {
    return "com.sourind.test.testorm.entity.Order1[id=" + id + "]";
}

}

提前致谢， 苏里

Answer 1

@Alex 这是ItemJpaController#destroy()的代码

public void destroy(Integer id) throws NonexistentEntityException {
    EntityManager em = null;
    try {
        em = getEntityManager();
        em.getTransaction().begin();
        Item item;
        try {
            item = em.getReference(Item.class, id);
            item.getId();
        } catch (EntityNotFoundException enfe) {
            throw new NonexistentEntityException("The item with id " + id + " no longer exists.", enfe);
        }
        Order1 order1 = item.getOrder1();
        if (order1 != null) {
            order1.getItemList().remove(item);
            order1 = em.merge(order1);
        }
        em.remove(item);
        em.getTransaction().commit();
    } finally {
        if (em != null) {
            em.close();
        }
    }
}

另外，我使用的hibernate版本没有DELETE_ORPHAN级联类型。

另外，我如何获得会话？我应该在destroy() 方法内的JpaController 类中还是在我从中创建/删除对象的邮件方法中获取它？

Answer 2

您应该能够删除订单记录并让它删除所有关联的项目记录。为此，您需要向 Order 和 Items 之间的关联添加另一个级联类型。

@OneToMany(cascade=CascadeType.ALL, mappedBy = "order1", fetch=FetchType.EAGER, orphanRemoval=true)
private List<Item> itemList;

这告诉 hibernate 当你删除父 Order 时它应该删除子 Item 记录。

session.delete(order);

此删除将级联到子项记录并将其删除。