双向@OneToOne 的问题

【问题标题】：Problem with bi-directional @OneToOne双向@OneToOne 的问题
【发布时间】：2011-01-28 02:55:32
【问题描述】：

我有 2 个实体客户和地址，如下所示： 客户.java

package com.hibernaterecipes.chapter5;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name="CUSTOMER")
public class Customer {
@Column (name="ID")
@Id
@GeneratedValue (strategy=GenerationType.AUTO)
private Long id;

@Column (name="COUNTRY_CODE")
private String countryCode;

@Column (name="ID_CARD_NO")
private String idCardNo;

@Column (name="FIRST_NAME")
private String firstName;

@Column (name="LAST_NAME")
private String lastName;

@Column (name="EMAIL")
private String email;

@OneToOne (cascade=CascadeType.ALL)
@JoinTable (name="CustomerAddress", 
        joinColumns=@JoinColumn(name="ID"),
        inverseJoinColumns=@JoinColumn(name="ADDRESS_ID"))
private Address address;

public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}
public String getCountryCode() {
    return countryCode;
}
public void setCountryCode(String countryCode) {
    this.countryCode = countryCode;
}
public String getIdCardNo() {
    return idCardNo;
}
public void setIdCardNo(String idCardNo) {
    this.idCardNo = idCardNo;
}
public String getFirstName() {
    return firstName;
}
public void setFirstName(String firstName) {
    this.firstName = firstName;
}
public String getLastName() {
    return lastName;
}
public void setLastName(String lastName) {
    this.lastName = lastName;
}

public String getEmail() {
    return email;
}
public void setEmail(String email) {
    this.email = email;
}
public Address getAddress() {
    return address;
}
public void setAddress(Address address) {
    this.address = address;
}

}

地址.java：

package com.hibernaterecipes.chapter5;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name="ADDRESS")
public class Address {
@Id
@Column (name="ADDRESS_ID")
@GeneratedValue (strategy=GenerationType.AUTO)
private Long id;

@Column(name="CITY")
private String city;

@Column(name="STREET")
private String street;

@Column(name="DOOR_PLATE")
private String doorplate;

@OneToOne (mappedBy="address")
private Customer customer;

public Customer getCustomer() {
    return customer;
}
public void setCustomer(Customer customer) {
    this.customer = customer;
}
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}
public String getCity() {
    return city;
}
public void setCity(String city) {
    this.city = city;
}
public String getStreet() {
    return street;
}
public void setStreet(String street) {
    this.street = street;
}
public String getDoorplate() {
    return doorplate;
}
public void setDoorplate(String doorplate) {
    this.doorplate = doorplate;
}

 }

当我尝试保留客户时，我得到以下堆栈跟踪：

Exception in thread "main" org.hibernate.PropertyValueException: not-null property references a null or transient value: com.hibernaterecipes.chapter5.Address.customer
at org.hibernate.engine.Nullability.checkNullability(Nullability.java:72)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:284)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:180)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:108)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:98)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:507)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:499)
at org.hibernate.engine.CascadingAction$5.cascade(CascadingAction.java:218)
at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:268)
at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:216)
at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:169)
at org.hibernate.engine.Cascade.cascade(Cascade.java:130)
at org.hibernate.event.def.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:412)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:261)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:180)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:108)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:535)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:523)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:519)
at com.hibernaterecipes.chapter5.Launch5_6A.main(Launch5_6A.java:29)

我尝试将@NotNull 添加到双方。@OneToOne 中的 optional = false 和 @JoinColumn 中的 unique = true, nullable = false 但没有任何效果。

图。帮助。

根据建议，我更改了地址类别

package com.hibernaterecipes.chapter5;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name="ADDRESS")
public class Address {
@Id
@Column (name="ADDRESS_ID")
@GeneratedValue (strategy=GenerationType.AUTO)
private Long id;

@Column(name="CITY")
private String city;

@Column(name="STREET")
private String street;

@Column(name="DOOR_PLATE")
private String doorplate;

@OneToOne(mappedBy="address")
private Customer customer;

public Customer getCustomer() {
    return customer;
}
public void setCustomer(Customer customer) {
    if (null != customer) {
        customer.setAddress(this);
        this.customer = customer;
    }
}
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}
public String getCity() {
    return city;
}
public void setCity(String city) {
    this.city = city;
}
public String getStreet() {
    return street;
}
public void setStreet(String street) {
    this.street = street;
}
public String getDoorplate() {
    return doorplate;
}
public void setDoorplate(String doorplate) {
    this.doorplate = doorplate;
}

}

客户类别保持不变。

用于测试代码助手类 JpaUtil.java

package persistence;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;

public class JpaUtil {
    private static SessionFactory sessionFactory;

      static {
        try {
           sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
        } catch (Throwable ex) {
           throw new ExceptionInInitializerError(ex);
        }
      }

      public static SessionFactory getSessionFactory() {
          // Alternatively, we could look up in JNDI here
          return sessionFactory;
      }

      public static void shutdown() {
          // Close caches and connection pools
          getSessionFactory().close();
      }
}

测试Launch5_6A.java的主类

package com.hibernaterecipes.chapter5;

import org.hibernate.Session;
import org.hibernate.Transaction;

import persistence.JpaUtil;

public class Launch5_6A {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Customer customer = new Customer();
        customer.setCountryCode("India");
        customer.setEmail("subhendu_mahanta@yahoo.com");
        customer.setFirstName("Subhendu");
        customer.setLastName("Mahanta");
        customer.setIdCardNo("43223");
        Address address = new Address();
        address.setCity("Pune");
        address.setDoorplate("E1/33");
        address.setStreet("Paud Road");
        address.setCustomer(customer);
        customer.setAddress(address);

        Session session = JpaUtil.getSessionFactory().openSession();
        Transaction tx = session.beginTransaction();
        session.save(customer);
        tx.commit();
        session.close();

    }

}

结果保持不变。

07:54:37,265  INFO Version:15 - Hibernate Annotations 3.2.0.CR3
07:54:37,296  INFO Environment:500 - Hibernate 3.2.0.cr5
...
Exception in thread "main" org.hibernate.PropertyValueException: not-null property references a null or transient value: com.hibernaterecipes.chapter5.Address.customer
    at org.hibernate.engine.Nullability.checkNullability(Nullability.java:72)
    at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:284)
    at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:180)
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:108)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:98)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
    at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:507)
    at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:499)
    at org.hibernate.engine.CascadingAction$5.cascade(CascadingAction.java:218)
    at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:268)
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:216)
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:169)
    at org.hibernate.engine.Cascade.cascade(Cascade.java:130)
    at org.hibernate.event.def.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:412)
    at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:261)
    at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:180)
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:108)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
    at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
    at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
    at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:535)
    at org.hibernate.impl.SessionImpl.save(SessionImpl.java:523)
    at org.hibernate.impl.SessionImpl.save(SessionImpl.java:519)
    at com.hibernaterecipes.chapter5.Launch5_6A.main(Launch5_6A.java:29)
07:54:39,734  INFO SchemaUpdate:160 - schema update complete
07:54:39,734 DEBUG DriverManagerConnectionProvider:129 - returning connection to pool, pool size: 1
07:54:39,734 DEBUG SessionFactoryImpl:390 - Checking 0 named HQL queries
07:54:39,734 DEBUG SessionFactoryImpl:410 - Checking 0 named SQL queries
07:54:39,796 DEBUG SessionImpl:220 - opened session at timestamp: 12963542797
07:54:39,796 DEBUG JDBCTransaction:54 - begin
07:54:39,796 DEBUG ConnectionManager:415 - opening JDBC connection
07:54:39,796 DEBUG DriverManagerConnectionProvider:93 - total checked-out connections: 0
07:54:39,796 DEBUG DriverManagerConnectionProvider:99 - using pooled JDBC connection, pool size: 0
07:54:39,796 DEBUG JDBCTransaction:59 - current autocommit status: false
07:54:39,796 DEBUG JDBCContext:210 - after transaction begin
07:54:39,796 DEBUG DefaultSaveOrUpdateEventListener:161 - saving transient instance
07:54:39,796 DEBUG AbstractSaveEventListener:152 - saving [com.hibernaterecipes.chapter5.Customer#<null>]
07:54:39,796 DEBUG AbstractSaveEventListener:240 - executing insertions
07:54:39,812 DEBUG Cascade:115 - processing cascade ACTION_SAVE_UPDATE for: com.hibernaterecipes.chapter5.Customer
07:54:39,812 DEBUG CascadingAction:216 - cascading to saveOrUpdate: com.hibernaterecipes.chapter5.Address
07:54:39,812 DEBUG AbstractSaveEventListener:489 - transient instance of: com.hibernaterecipes.chapter5.Address
07:54:39,812 DEBUG DefaultSaveOrUpdateEventListener:161 - saving transient instance
07:54:39,812 DEBUG AbstractSaveEventListener:152 - saving [com.hibernaterecipes.chapter5.Address#<null>]
07:54:39,812 DEBUG AbstractSaveEventListener:240 - executing insertions

【问题讨论】：

  • 我建议你在你的帖子中添加一个 java 标签
  • 我认为，使 nullable=true 或从两侧设置对象，例如 cutomer.setAddress(addr) 和 address.setCustomer(cust)。

标签： hibernate


【解决方案1】：

我相信这目前是 Hibernate 中的一个限制（它实际上并没有将空值持久化到数据库，因为您使用的是 JoinTable，但它认为它是）。我们已经能够不在实体中提取可空/可选标志，而是在数据库模式本身中强制执行不可空性。它不太理想，但它可以工作，并且您确实获得了引用完整性（您可以添加一个 prePersist 和 postLoad 侦听器以确保您甚至不尝试数据库写入）。

【讨论】：

  • 所以在hibernate中使用连接表和使用@OneToOne的双向一对一关联是不可能的。我们选择JoinColumn，即外键关联或共享主键。
  • FK 不起作用，因为您会在数据库中看到先有鸡还是先有蛋的问题（您首先保存哪个实体？）。共享主键应该可以工作。同样，在休眠中使用连接表和@OneToOne works 进行双向一对一关联，您只是不能在代码中声明它们为非空（但只能在数据库中）。跨度>
  • 这不是鸡蛋问题，因为有一方“拥有”这种关系。在这种情况下，它是客户。
  • 当然，我确信双向一对一映射在休眠模式下使用正确的模式工作，如果你想要一个单向映射，即地址可能有也可能没有一个唯一的客户绑定对它，你当然可以做到。您的回答不会强制执行 nullable=false，如果您尝试这样做，hibernate 会抱怨。
  • ic，也许我明天应该试一试，也许那时我们正在运行旧版本
【解决方案2】：

我认为将地址设置为可嵌入对象会更好地处理这种情况，但这是您的选择。

但无论如何，将@OneToOne 与@JoinTable 映射是完全可能的。您只需要分两步完成。请参阅此代码：

public class Address {
    @Id @GeneratedValue
    private Long id;

    @Column
    private String name;

    @OneToOne(mappedBy="address")
    private Customer customer;

    public void setCustomer(Customer c) {
        if (null != c) {
            c.setAddress(this);
            this.customer = c;
        }
    }
}

public class Customer {
    @Id @GeneratedValue
    private Long id;

    @Column
    private String name;

    @OneToOne
    @JoinTable(name = "CustomerAddress")
    private Address address;
}

在您的业务方法中：

    Customer c = new Customer();
    c.setName("c1");

    Address a = new Address();
    a.setName("a1");

    em.getTransaction().begin();

    em.persist(c);

    a.setCustomer(c);
    em.persist(a);

    em.getTransaction().commit();

此代码将生成这些 SQL 指令：

Hibernate: insert into Customer (id, name) values (null, ?)
Hibernate: insert into Address (id, name) values (null, ?)
Hibernate: insert into CustomerAddress (address_id, id) values (?, ?)

【讨论】：

  • 嗨，Partenon，根据您的建议，我更改了地址类并保留客户原样。仍然无法正常工作。请参阅我编辑的帖子。谢谢。
  • 再次查看我关于业务方法的示例（在您的情况下为 Launch5_6A）。先坚持客户，再给客户设置地址，再坚持地址。另外，请保持您的问题干净，目前很难使用如此多的样板代码和重复示例...
猜你喜欢
  • 1970-01-01
  • 1970-01-01
  • 2012-09-28
  • 1970-01-01
  • 1970-01-01
  • 2012-03-14
  • 2012-10-14
  • 1970-01-01
  • 1970-01-01
相关资源
最近更新 更多
热门标签
Java Python linux javascript Mysql C# Docker 算法 前端 SpringBoot Redis Vue spring 设计模式 .net core .net kubernetes c++ 数据库 数据结构 大数据 js 机器学习 微服务 Android Go 程序员 面试 JVM ASP.net core 云原生 人工智能 后端 PHP git CSS golang k8s Nginx Django mybatis 深度学习 多线程 React 架构 devops 爬虫 云计算 Spring Boot LeetCode