[FIXED] Register Hibernate 5 Event Listeners

Issue

I am working on a legacy non-Spring application, and it is being migrated from Hibernate 3 to Hibernate 5.6.0.Final (latest at this time). I have generally never used Hibernate Event Listeners in my work, so this is quite new to me, and I am studying these in Hibernate 5.

Currently in some test class we have defined the code this way for Hibernate 3:

protected static Configuration createSecuredDatabaseConfig()  {
    Configuration config = createUnrestrictedDatabaseConfig();
    config.setListener("pre-insert", "com.app.server.services.db.eventlisteners.MySecurityHibernateEventListener");
    config.setListener("pre-update", "com.app.server.services.db.eventlisteners.MySecurityHibernateEventListener");
    config.setListener("pre-delete", "com.app.server.services.db.eventlisteners.MySecurityHibernateEventListener");
    config.setListener("pre-load", "com.app.server.services.db.eventlisteners.EkoSecurityHibernateEventListener");
    return config;
}

This is obviously no longer valid, and I believe I need to create a Hibernate Integrator, which I have done.

public class MyEventListenerIntegrator implements Integrator {

@Override
public void integrate(Metadata metadata, SessionFactoryImplementor sessionFactory,
        SessionFactoryServiceRegistry serviceRegistry) {
    EventListenerRegistry eventListenerRegistry = serviceRegistry.getService(EventListenerRegistry.class);
    
    eventListenerRegistry.getEventListenerGroup(EventType.PRE_INSERT).appendListener(new MySecurityHibernateEventListener());
    eventListenerRegistry.getEventListenerGroup(EventType.PRE_UPDATE).appendListener(new MySecurityHibernateEventListener());
    eventListenerRegistry.getEventListenerGroup(EventType.PRE_DELETE).appendListener(new MySecurityHibernateEventListener());
    eventListenerRegistry.getEventListenerGroup(EventType.PRE_LOAD).appendListener(new MySecurityHibernateEventListener());
}

So, now I believe the next step is to add this to the session via the registry builder. I am using this website to help me:

https://www.boraji.com/hibernate-5-event-listener-example

Because we were using older Hibernate 3, we had code to create our session factory as follows:

protected static SessionFactory buildSessionFactory(Database db)
{
    if (db == null) {
        throw new NullPointerException("Database specifier cannot be null");
    }
    
    try {
        Configuration config = createSessionFactoryConfiguration(db);
        String url = config.getProperty("connection.url");
        String user = config.getProperty("connection.username");
        String password = config.getProperty("connection.password");           

        try {
            String dbDriver = config.getProperty("hibernate.connection.driver_class");
            Class.forName(dbDriver);
            Connection conn = DriverManager.getConnection(url, user, password);
        }
        catch (SQLException error)  {
            logger.info("Didn't find driver, on QA or production, so it's okay to assume we have DB connection");
            error.printStackTrace();
        }
        SessionFactory sessionFactory = config.buildSessionFactory();
        sessionFactoryConfigs.put(sessionFactory, config); // Cannot recover config from factory instance, must be stored.
        return sessionFactory;
    }
    catch (Throwable ex) {
        // Make sure you log the exception, as it might be swallowed
        logger.error("Initial SessionFactory creation failed.", ex);
        throw new ExceptionInInitializerError(ex);
    }
}

The link that I referred to above has a much different way of creating the sessionfactory. So, I'll be testing that out to see if it works in our app.

Without Spring handling our sessions and transactions, in this app it is coded by hand the way it was done before Spring, and I haven't seen that kind of code in years.

Solution

I solved this issue with the help from the link I provided above. However, I didn't copy exactly what they did, but some of it helped. My solution is as follows:

protected static SessionFactory createSecuredDatabaseConfig() {
    Configuration config = createUnrestrictedDatabaseConfig();
    
    BootstrapServiceRegistry bootstrapRegistry =
            new BootstrapServiceRegistryBuilder()
            .applyIntegrator(new EkoEventListenerIntegrator())
            .build();
    
    ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder(bootstrapRegistry).applySettings(config.getProperties()).build();
    
    SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistry);
    
    return sessionFactory;
}

This was it. I tried multiple different ways to register the events without the BootstrapServiceRegistry, but none of those worked. I did have to create the integrator. What I did NOT include was the following:

MetadataSources sources = new MetadataSources(serviceRegistry )
              .addPackage("com.myproject.server.model");
Metadata metadata = sources.getMetadataBuilder().build();

// did not create the sessionFactory this way
sessionFactory = metadata.getSessionFactoryBuilder().build();

If I had gone further and use this method to create the sessionFactory, then all of my queries would have been complaining about not being able to find the parameterName, which is something else.

The Hibernate Integrator and this method to create the sessionFactory is all for the unit tests. Without registering these events, one unit test would fail, and now it doesn't. So, this solves my problem for now.

Answered By - tjholmes66
Answer Checked By - Timothy Miller (JavaFixing Admin)