JPA/Hibernate:反向OneToOne孤立删除约束冲突 问题:
我在父母和孩子之间有一个@OneToOne关系,该关系由孩子映射,并且孤儿移除设置为true。孩子还与第三个实体有@manytomy关系 当将子项设置为null(希望删除子项)时,我得到一个完整性约束冲突:外键 测试模型: 导师与学生有一对一的关系,后者与课程实体有许多关系:JPA/Hibernate:反向OneToOne孤立删除约束冲突 问题:,hibernate,jpa,constraints,one-to-one,orphan,Hibernate,Jpa,Constraints,One To One,Orphan,我在父母和孩子之间有一个@OneToOne关系,该关系由孩子映射,并且孤儿移除设置为true。孩子还与第三个实体有@manytomy关系 当将子项设置为null(希望删除子项)时,我得到一个完整性约束冲突:外键 测试模型: 导师与学生有一对一的关系,后者与课程实体有许多关系: OneTONE关系由Student.tutor映射(学生表中的ID\u tutor外键列) 级联=全部 删除=真 多人关系保存在连接表STUDENT_COURSE中,外键指向STUDENT表和COURSE表 我正在
- OneTONE关系由Student.tutor映射(学生表中的ID\u tutor外键列)
- 级联=全部
- 删除=真
- 多人关系保存在连接表STUDENT_COURSE中,外键指向STUDENT表和COURSE表
@实体
公开课导师{
私人长id;
私有字符串名称;
私立学生;
公共导师(){super();}
公共导师(字符串名称,学生){
超级();
this.name=名称;
设置学生(学生);
}
@身份证
@生成值
public Long getId(){return id;}
public void setId(长id){this.id=id;}
公共字符串getName(){return name;}
public void setName(字符串名){this.name=name;}
@OneTONE(cascade=CascadeType.ALL,orphanRemoving=true,mappedBy=“tutor”)
公共学生getStudent(){return Student;}
公立学校学生(学生){
这个。学生=学生;
如果(学生!=null){
student.setTutor(本);
}
}
}
@实体
公立班学生{
私人长id;
私有字符串名称;
私人地图课程;
私人家教;
公立学生(){super();}
公立学生(字符串名称、地图课程){
超级();
this.name=名称;
本课程=课程;
}
@身份证
@生成值
public Long getId(){return id;}
public void setId(长id){this.id=id;}
公共字符串getName(){return name;}
public void setName(字符串名){this.name=name;}
@许多
公共地图getCourses(){return courses;}
公共课程(地图课程){this.courses=courses;}
@奥内托内
公共导师getutor(){return Tutor;}
public void setTutor(Tutor Tutor){this.Tutor=Tutor;}
}
@实体
公共课{
私人长id;
私有字符串名称;
公共课程(){super();}
公共课程(字符串名称){
超级();
this.name=名称;
}
@身份证
@生成值
public Long getId(){return id;}
public void setId(长id){this.id=id;}
公共字符串getName(){return name;}
public void setName(字符串名){this.name=name;}
}
公共类CheckManyToManyDeletion{
私有静态最终记录器Logger=Logger.getLogger(CheckManyToManyDeletation.class);
私有静态SessionFactory SessionFactory;
公共静态void main(字符串[]args){
configure(“log4j config.xml”);
类[]映射=新类[]{Tutor.Class、Student.Class、Course.Class};
创建表(映射);
sessionFactory=DBUtils.createSessionFactory(映射);
试一试{
long tutoroid=initialImport();
Session Session=sessionFactory.openSession();
事务tx=会话.beginTransaction();
Tutor Tutor=session.get(Tutor.class,tutorId);
logger.info(“删除学生”);
tutor.setStudent(空);
tx.commit();
}最后{
sessionFactory.close();
}
}
私有静态长initialImport(){
Session Session=sessionFactory.openSession();
事务tx=会话.beginTransaction();
学生=新生();
学生名称(“学生”);
Map courses=newhashmap();
学生课程;
对于(int i=0;i<5;i++){
课程=新课程();
课程名称(“课程”+i);
保存(课程);
courses.put(course.getName(),courses);
}
导师=新导师(“导师”,学生);
session.save(导师);
tx.commit();
session.close();
返回tutor.getId();
}
}
笔记:
实际上,我们的应用程序附带了一个巨大的数据模型:
- 持久化和删除实体是通过级联实现的
- 我们反转OneToOne关系,为子对象提供与其父对象相同的id(通过@MapsId)
@Entity
public class Tutor {
private Long id;
private String name;
private Student student;
public Tutor() { super(); }
public Tutor(String name, Student student) {
super();
this.name = name;
setStudent(student);
}
@Id
@GeneratedValue
public Long getId() { return id; }
public void setId(Long id) { this.id = id; }
public String getName() { return name; }
public void setName(String name) { this.name = name; }
@OneToOne(cascade=CascadeType.ALL, orphanRemoval=true, mappedBy="tutor")
public Student getStudent() { return student; }
public void setStudent(Student student) {
this.student = student;
if(student != null) {
student.setTutor(this);
}
}
}
@Entity
public class Student {
private Long id;
private String name;
private Map<String, Course> courses;
private Tutor tutor;
public Student() { super(); }
public Student(String name, Map<String, Course> courses) {
super();
this.name = name;
this.courses = courses;
}
@Id
@GeneratedValue
public Long getId() { return id; }
public void setId(Long id) { this.id = id; }
public String getName() { return name; }
public void setName(String name) { this.name = name; }
@ManyToMany
public Map<String, Course> getCourses() { return courses; }
public void setCourses(Map<String, Course> courses) { this.courses = courses; }
@OneToOne
public Tutor getTutor() { return tutor; }
public void setTutor(Tutor tutor) { this.tutor = tutor; }
}
@Entity
public class Course {
private Long id;
private String name;
public Course() { super(); }
public Course(String name) {
super();
this.name = name;
}
@Id
@GeneratedValue
public Long getId() { return id; }
public void setId(Long id) { this.id = id; }
public String getName() { return name; }
public void setName(String name) { this.name = name; }
}
public class CheckManyToManyDeletation {
private static final Logger logger = Logger.getLogger(CheckManyToManyDeletation.class);
private static SessionFactory sessionFactory;
public static void main(String[] args) {
DOMConfigurator.configure("log4j-config.xml");
Class[] mappings = new Class[] {Tutor.class, Student.class, Course.class};
DBUtils.createTables(mappings);
sessionFactory = DBUtils.createSessionFactory(mappings);
try {
long tutorId = initialImport();
Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
Tutor tutor = session.get(Tutor.class, tutorId);
logger.info("DeletingStudent");
tutor.setStudent(null);
tx.commit();
} finally {
sessionFactory.close();
}
}
private static long initialImport() {
Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
Student student = new Student();
student.setName("student");
Map<String, Course> courses = new HashMap<>();
student.setCourses(courses);
for (int i = 0; i < 5; i++) {
Course course = new Course();
course.setName("course" + i);
session.save(course);
courses.put(course.getName(), course);
}
Tutor tutor = new Tutor("tutor", student);
session.save(tutor);
tx.commit();
session.close();
return tutor.getId();
}
}