Integration of T5 with the domain model

[Leon Pennings <L....@kenict.org>]

Just wanted to share how I hooked up T5 with my domain model.
I'm using jpa for persistence, so the thing I needed was injection of
the EntityManager into the objects providing access to my top level
domain objects.
And for just that simple IoC, Spring is way too overkill. Guice on the
other hand was quite nice for it.

I integrated it like this:

The access object

public class BlaBlaJPAQuery implements BlaBlaFinder {
   @Inject //the guice inject annotation
   private EntityManager _entityManager;

   //Code...
}

the JPAUtil

public class JPAUtil implements Provider<EntityManager> {

   private static final EntityManagerFactory _entityManagerFactory;
   
   private static ThreadLocal<EntityManager> _entityManagerContainer;
   
   static {
      _entityManagerFactory =
Persistence.createEntityManagerFactory("POB");
	_entityManagerContainer = new ThreadLocal<EntityManager>();
   }
   
   public static void createEntityManager() {
 
_entityManagerContainer.set(_entityManagerFactory.createEntityManager())
;
   }
    
   public static void closeEntityManager() {
      EntityManager entityManager = _entityManagerContainer.get();
      entityManager.close();
   }

   public EntityManager get() {
      return _entityManagerContainer.get();
   }
   
}

Another filter before the T5 filter that does this:

   public void doFilter(ServletRequest request, ServletResponse
response, FilterChain filterChain) throws IOException, ServletException
{
     try {
        JPAUtil.createEntityManager();
        filterChain.doFilter(request, response);
     } finally {
        JPAUtil.closeEntityManager();
     }
   }

The Guice module:

public class POBGuiceModule extends AbstractModule {

   public void configure() {
      bind(EntityManager.class).toProvider(JPAUtil.class);
   }

}

And the T5 module:

public class POBTapestryModule {

   private static final Injector _injector;
  
   static {
      _injector = Guice.createInjector(new Module[] { new
POBGuiceModule() });
   }
   
   @Lifecycle(value="perthread")
   public static BlaBlaFinder buildBlaBlaFinder() {
      return _injector.getInstance(BlaBlaJPAQuery.class);
   }

}

And offcourse the page:

   @Inject //T5 inject annotation
   private BlaBlaFinder _blablaFinder;

Comments/Suggestions/missed design flaws?



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