Hibernate: Automatically creating/updating the db tables based on entity classes

Question

I have the following entity class (in Groovy):

import javax.persistence.Entity import javax.persistence.Id import javax.persistence.GeneratedValue import javax.persistence.GenerationType  @Entity public class ServerNode {    @Id   @GeneratedValue(strategy = GenerationType.AUTO)   Long id    String firstName   String lastName  } 

and my persistence.xml:

<?xml version="1.0" encoding="UTF-8"?> <persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">     <persistence-unit name="NewPersistenceUnit">         <provider>org.hibernate.ejb.HibernatePersistence</provider>         <properties>             <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/Icarus"/>             <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>             <property name="hibernate.connection.username" value="root"/>             <property name="hibernate.connection.password" value=""/>             <property name="hibernate.archive.autodetection" value="class"/>             <property name="hibernate.show_sql" value="true"/>             <property name="hibernate.format_sql" value="true"/>             <property name="hbm2ddl.auto" value="create"/>         </properties>         <class>net.interaxia.icarus.data.models.ServerNode</class>     </persistence-unit> </persistence> 

and the script:

import javax.persistence.EntityManager import javax.persistence.EntityManagerFactory import javax.persistence.Persistence import net.interaxia.icarus.data.models.ServerNode  def factory = Persistence.createEntityManagerFactory("NewPersistenceUnit") def manager = factory.createEntityManager()  manager.getTransaction().begin()  manager.persist new ServerNode(firstName: "Test", lastName: "Server")  manager.getTransaction().commit() 

the database Icarus exists, but currently has no tables. I would like Hibernate to automatically create and/or update the tables based on the entity classes. How would I accomplish this?

Answer 1

I don't know if leaving hibernate off the front makes a difference.

The reference suggests it should be hibernate.hbm2ddl.auto

A value of create will create your tables at sessionFactory creation, and leave them intact.

A value of create-drop will create your tables, and then drop them when you close the sessionFactory.

Perhaps you should set the javax.persistence.Table annotation explicitly?

Hope this helps.

Answer 2

You might try changing this line in your persistence.xml from

<property name="hbm2ddl.auto" value="create"/> 

to:

<property name="hibernate.hbm2ddl.auto" value="update"/> 

This is supposed to maintain the schema to follow any changes you make to the Model each time you run the app.

Got this from JavaRanch