| Is TABLE_PER_CLASS supposed to work with eclipselink-2.0.0.v20090731-r4765 (m6) [message #481227] |
Thu, 20 August 2009 04:08  |
 Martin
Messages: 35
Registered: July 2009 |
Member |
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Hello,
I would like to know if InheritanceType.TABLE_PER_CLASS is supposed to
work with eclipselink-2.0.0.v20090731-r4765 (milestone 6). If I try to use
it I always get the following exception for ManyToMany bidirectional
relations:
[java] Exception [EclipseLink-80] (Eclipse Persistence Services -
2.0.0.v20090731-r4765):
org.eclipse.persistence.exceptions.DescriptorException
[java] Exception Description: The relation key field
[DEPARTMENT.departments_ID] for this mapping must exist in the relation
table.
[java] Mapping:
org.eclipse.persistence.mappings.ManyToManyMapping[students]
[java] Descriptor: RelationalDescriptor(Department -->
[DatabaseTable(DEPARTMENT)])
Best regards,
Martin
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| Re: Is TABLE_PER_CLASS supposed to work with eclipselink-2.0.0.v20090731-r4765 (m6) [message #482163 is a reply to message #481849] |
Tue, 25 August 2009 10:50  |
No real name
Messages: 5
Registered: August 2009 |
Junior Member |
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For my example I'm using the following two entity classes Student and Department:
import java.util.*;
import javax.persistence.*;
@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public class Student {
@Id
@GeneratedValue(strategy=GenerationType.TABLE)
private int id;
private String name;
@ManyToMany
private Collection<Department> departments;
public Student() {
departments = new ArrayList<Department>();
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public void addDepartment(Department department) {
if (!getDepartments().contains(department)) {
getDepartments().add(department);
}
if (!department.getStudents().contains(this)) {
department.getStudents().add(this);
}
}
public Collection<Department> getDepartments() {
return departments;
}
public void setDepartment(Collection<Department> departments) {
this.departments = departments;
}
public String toString() {
return "Student id: " + getId() + ", name: " + getName();
}
}
import java.util.*;
import javax.persistence.*;
@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public class Department {
@Id
@GeneratedValue(strategy=GenerationType.TABLE)
private int id;
private String name;
@ManyToMany(mappedBy="departments")
private Collection<Student> students;
public Department(){
students = new ArrayList<Student>();
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String deptName) {
this.name = deptName;
}
public void addStudent(Student student) {
if (!getStudents().contains(student)) {
getStudents().add(student);
}
if (!student.getDepartments().contains(this)) {
student.getDepartments().add(this);
}
}
public Collection<Student> getStudents() {
return students;
}
public void setStudent(Collection<Student> students) {
this.students = students;
}
public String toString() {
return "Department id: " + getId() + ", name: " + getName();
}
}
I have a simple Main class which just does:
import java.util.*;
import javax.persistence.*;
public class Main {
public static void main(String[] args) throws Exception {
if (args.length != 1) {
System.err.println("No provider (hibernate|eclipselink) specified.");
System.exit(1);
}
String provider = args[0];
EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService_"+provider);
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
Student student1 = new Student();
em.persist(student1);
student1.setName("Joe");
Student student2 = new Student();
em.persist(student2);
student2.setName("Tom");
Department dept = new Department();
em.persist(dept);
dept.setName("MyDepartment");
dept.addStudent(student1);
dept.addStudent(student2);
em.flush();
em.getTransaction().commit();
System.out.println("Students:");
Query query = em.createQuery("SELECT e FROM Student e");
List<Student> students = (List<Student>) query.getResultList();
for (Student student : students) {
System.out.println(student);
}
System.out.println("Departments:");
query = em.createQuery("SELECT d FROM Department d");
List<Department> departments = (List<Department>) query.getResultList();
for (Department department : departments) {
System.out.println(department);
}
em.close();
emf.close();
}
}
I'm using the following persistence.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="JPAService_hibernate" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>Department</class>
<class>Student</class>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
<property name="hibernate.connection.username" value="sa"/>
<property name="hibernate.connection.password" value=""/>
<property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
</properties>
</persistence-unit>
<persistence-unit name="JPAService_eclipselink" transaction-type="RESOURCE_LOCAL">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>Department</class>
<class>Student</class>
<properties>
<property name="eclipselink.ddl-generation" value="create-tables"/>
<property name="eclipselink.ddl-generation.output-mode" value="database"/>
<property name="eclipselink.target-server" value="none"/>
<property name="eclipselink.target-database" value="HSQL"/>
<property name="javax.persistence.jdbc.user" value="sa"/>
<property name="javax.persistence.jdbc.password" value=""/>
<property name="javax.persistence.jdbc.url" value="jdbc:hsqldb:data/tutorial"/>
<property name="javax.persistence.jdbc.driver" value="org.hsqldb.jdbcDriver"/>
<property name="eclipselink.logging.logger" value="JavaLogger"/>
<property name="eclipselink.logging.level" value="FINEST"/>
</properties>
</persistence-unit>
</persistence>
When using hibernate as a persistence provider everything works as expected. When using eclipselink the code throws exceptions as shown in my first message. I would be very happy if someone could tell me what's wrong with the code.
Best regards,
Martin
[Updated on: Tue, 25 August 2009 11:25] Report message to a moderator |
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