Auto generate data schema from JPA annotated entity classes

Question

I\'m using JPA (Hibernate\'s implementation) to annotate entity classes to persist to a relational database (MySQL or SQL Server). Is there an easy way to auto generate the

Answer 1

As Hibernate 4.3+ now implements JPA 2.1 the appropriate way to generate DDL scripts is to use following set of JPA 2.1 properties :

As it will be run at runtime, you may want to execute this DDL generation at build. There is no supported official maven plugin anymore for Hibernate4 probably because Hibernate team is moving to Gradle.

Anyway, this is the JPA 2.1 approach to generate this script programmatically :

import java.io.IOException;
import java.util.Properties;

import javax.persistence.Persistence;

import org.hibernate.jpa.AvailableSettings;

public class JpaSchemaExport {

    public static void main(String[] args) throws IOException {
        execute(args[0], args[1]);
        System.exit(0);
    }

    public static void execute(String persistenceUnitName, String destination) {
        System.out.println("Generating DDL create script to : " + destination);

        final Properties persistenceProperties = new Properties();

        // XXX force persistence properties : remove database target
        persistenceProperties.setProperty(org.hibernate.cfg.AvailableSettings.HBM2DDL_AUTO, "");
        persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_DATABASE_ACTION, "none");

        // XXX force persistence properties : define create script target from metadata to destination
        // persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_CREATE_SCHEMAS, "true");
        persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_SCRIPTS_ACTION, "create");
        persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_CREATE_SOURCE, "metadata");
        persistenceProperties.setProperty(AvailableSettings.SCHEMA_GEN_SCRIPTS_CREATE_TARGET, destination);

        Persistence.generateSchema(persistenceUnitName, persistenceProperties);
    }

}

As you can see it's very simple !

You can now use this in an AntTask, or MAVEN build like this (for MAVEN) :

            
                maven-antrun-plugin
                1.7
                
                    
                        generate-ddl-create
                        process-classes
                        
                            run