Teneo/Hibernate/Tutorial

This tutorial shows how EMF, Teneo and Hibernate work together to automatically create the database schema and persist EMF objects. The tutorial also shows examples of HQL queries for EMF object and using the EMF Hibernate resource.

This tutorial uses the example project which you can download here.

This tutorial assumes some basic knowledge of EMF. If you are new to EMF then it can make sense to first try one of the core EMF tutorials which you can find here.

Initial Setup

The tutorial assumes that you have a running Eclipse with EMF and Teneo installed. In addition the Teneo dependencies (incl. hsqldb and mysql drivers) should be installed. See the Download & Install page for more information.

This tutorial uses hsqldb but it can easily be changed to use mysql or another database. For other databases than hsqldb and mysql you need to take make sure that the jdbc driver is in the classpath of the org.eclipse.emf.teneo.hibernate.examples project.

For mysql and other non-in-memory databases you have to create the database up-front (so not the tables inside the database but just the database itself). For this tutorial the database name should be: library.

Running the tutorial

After downloading the examples project from cvs you can directly run the tutorial. Open the project and navigate to the Tutorial.java file and right click and select 'Run As > Java Application'. You will see several things getting printed to the console (one of them is the generated Hibernate mapping).

This run takes the following steps:

• reads the EPackage model from the generated EPackage file.
• generate a hibernate mapping for the EPackage
• create the database (on hsqldb)
• create objects and persist them
• read the objects back using queries
• make changes, add new objects and persist them
• read and update the objects an EMF Hibernate resource

Walk-Through

The tutorial java class executes several steps. The initialization part calls Teneo directly, in the remaining runtime steps only EMF and Hibernate are directly used.

Initialization

The initialization starts by setting both Hibernate as well as Teneo properties in a properties map:

// To configure Hibernate, supply properties describing the JDBC driver,
// URL, username/password and SQL dialect.
// By default the properties are obtained from the file
// "hibernate.properties" at the classpath root.
//
// Alternatively, you can set the properties programmatically:
// 
// For more information see <a
// href="http://www.hibernate.org/hib_docs/v3/reference/en/html/session-configuration.html#configuration-programmatic">
// section 3.1 of the Hibernate manual</a>.
//
Properties hibernateProperties = new Properties();
 
//
// 1) From a ".properties" file or stream.
// InputStream in = ...
// hibernateProperties.load(in);
//
// 2) or populated manually:
//		hibernateProperties.setProperty(Environment.DRIVER, "com.mysql.jdbc.Driver");
//		hibernateProperties.setProperty(Environment.USER, "root");
//		hibernateProperties.setProperty(Environment.URL, "jdbc:mysql://127.0.0.1:3306/library");
//		hibernateProperties.setProperty(Environment.PASS, "root");
//		hibernateProperties.setProperty(Environment.DIALECT, "org.hibernate.dialect.MySQLInnoDBDialect");
 
hibernateProperties.setProperty(Environment.DRIVER, "org.hsqldb.jdbcDriver");
hibernateProperties.setProperty(Environment.USER, "sa");
hibernateProperties.setProperty(Environment.URL, "jdbc:hsqldb:file:/tmp/hsqldb");
hibernateProperties.setProperty(Environment.PASS, "");
hibernateProperties.setProperty(Environment.DIALECT, org.hibernate.dialect.HSQLDialect.class.getName());

Teneo has many configuration options, these are set as follows:

// set a specific option
// see this page http://wiki.eclipse.org/Teneo/Hibernate/Configuration_Options
// for all the available options
hibernateProperties.setProperty(PersistenceOptions.CASCADE_POLICY_ON_NON_CONTAINMENT, "REFRESH,PERSIST,MERGE");

Then a datastore is created. The datastore manages the persistence of one or more EPackages. It takes care of generating the model-relational mapping and initialization of Hibernate. The last step of the initialization is creating the session factory. The session factory is used at runtime in the next steps.

// Create the DataStore.
final String dataStoreName = "LibraryDataStore";
final HbDataStore dataStore = HbHelper.INSTANCE.createRegisterDataStore(dataStoreName);
dataStore.setProperties(hibernateProperties);
 
// Configure the EPackages used by this DataStore.
dataStore.setEPackages(new EPackage[] { ExtlibraryPackage.eINSTANCE });
 
// Initialize the DataStore. This sets up the Hibernate mapping and, in
// turn, creates the corresponding tables in the database.
try {
	dataStore.initialize();
} finally {
			// print the hibernate mapping
	System.err.println(dataStore.getMappingXML());
}
 
final SessionFactory sessionFactory = dataStore.getSessionFactory();

Persisting EMF Objects

The next step creates a number of EMF objects and persists them:

// Open a new Session and start transaction.
final Session session = sessionFactory.openSession();
session.beginTransaction();
 
// Create a library.
Library library = ExtlibraryFactory.eINSTANCE.createLibrary();
library.setName("My Library");
// Make it persistent.
session.save(library);
 
// Create a writer and book...
... code truncated ...
 
// Commit the changes to the database.
session.getTransaction().commit();
// Close the session. Not necessary if
session.close();