Generate DDL for JPA 2.0 with EclipseLink

I've created my model classes with JPA 2.0 annotations. At runtime, I will use EclipseLink 2.2.0, but I've been careful to use only pure JPA annotations in my model classes.

Now, how do I generate the schema DDL for the database ?

I want to use the EclipseLink API to generate the D开发者_Go百科DL from the classes, but not at runtime. Instead, I want a Java class to run on the command line and which outputs the DDL. What this guy did for Hibernate, I want for EclipseLink.

I'd also settle for an Ant task or some plugin for Maven.

Also, I chose to name my file jpa.xml instead of persistence.xml; bonus points if your solution accounts for this as well. Otherwise, I'll just rename my file persistence.xml.

You can find your answers in the EclipseLink Documentation, more specifically in the section called Using EclipseLink JPA Extensions for Schema Generation.

There you will find that there is a property called eclipselink.ddl-generation with possible values like NONE | CREATE_ONLY | DROP_AND_CREATE.

There you will find an additional property named eclipselink.ddl-generation.output-mode, whose documentation is in this same page.

It will provide you control on whether you want just to generate a script or actually execute the DDL against the database.

I hope that helps!

I know this is a little late but I have been struggling with the same problem. What I found was after doing the configurations like setting the "eclipselink.ddl-generation", then I hooked the following code into our build I got ddl file to generate. EntityManagerHolder class would have to be defined in your context.xml. It is a bit hackish but works.

public class EntityManagerHolder {
  @PersistenceContext(type = PersistenceContextType.TRANSACTION)
  private EntityManager entityManager;
  protected EntityManager getEntityManager() {
    return entityManager;
  }
}

public class SQLGeneration {
  public static void generateSQLFiles() {
ClassPathXmlApplicationContext application_context = new ClassPathXmlApplicationContext(
    "META-INF" + File.separator + "spring" + File.separator
        + "context.xml");
EntityManagerHolder entity_manager_holder = (EntityManagerHolder) application_context
    .getBean("entityManagerHolder");
entity_manager_holder.getEntityManager().getEntityManagerFactory()
    .createEntityManager();
  }
}