I'm new to JPA and I'm having problems with the autogeneration of primary key values.
I have the following entity:
package jpatest.entities;
import
java.io.Serializable;
import javax.
persistence.Entity;
import javax.
persistence.GeneratedValue;
import javax.
persistence.GenerationType;
import javax.
persistence.Id;
@Entity
public class MyEntity implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
private String someProperty;
public String getSomeProperty() {
return someProperty;
}
public void setSomeProperty(String someProperty) {
this.someProperty = someProperty;
}
public MyEntity() {
}
public MyEntity(String someProperty) {
this.someProperty = someProperty;
}
@Override
public String toString() {
return "jpatest.entities.MyEntity[id=" + id + "]";
}
}
and the following main method in other class:
public static void main(String[] args) {
EntityManagerFactory emf =
Persistence.createEntityManagerFactory("JPATestPU");
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
MyEntity e = new MyEntity("some value");
em.persist(e); /* (exception thrown here) */
em.getTransaction().commit();
em.close();
emf.close();
}
This is my
persistence unit:
<?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="JPATestPU" transaction-type="RESOURCE_LOCAL">
<provider>oracle.toplink.essentials.PersistenceProvider</provider>
<class>jpatest.entities.MyEntity</class>
<properties>
<property name="toplink.jdbc.user" value="..."/>
<property name="toplink.jdbc.password" value="..."/>
<property name="toplink.jdbc.url" value="jdbc:mysql://localhost:3306/jpatest"/>
<property name="toplink.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="toplink.ddl-generation" value="create-tables"/>
</properties>
</persistence-unit>
</persistence>
When I execute the program I get the following exception in the line marked with the proper comment:
Exception in thread "main"
java.lang.IllegalArgumentException: Object: jpatest.entities.MyEntity[id=null] is not a known entity type.
at oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl.registerNewObjectForPersist(UnitOfWorkImpl.java:3212)
at oracle.toplink.essentials.internal.ejb.cmp3.base.EntityManagerImpl.persist(EntityManagerImpl.java:205)
at jpatest.Main.main(Main.java:...)
What am I missing?
