maint-5-2/tapestry-hibernate/src/main/java/org/apache/tapestry5/internal/hibernate/EntityApplicationStatePersistenceStrategy.java

// Copyright 2009 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package org.apache.tapestry5.internal.hibernate;

import java.io.Serializable;

import org.apache.tapestry5.internal.services.SessionApplicationStatePersistenceStrategy;
import org.apache.tapestry5.services.ApplicationStateCreator;
import org.apache.tapestry5.services.Request;
import org.hibernate.HibernateException;

/**
 * Persists Hibernate entities as SSOs by storing their primary key in the {@link org.apache.tapestry5.services.Session}.
 * 
 * @see org.apache.tapestry5.internal.hibernate.PersistedEntity
 */
public class EntityApplicationStatePersistenceStrategy extends SessionApplicationStatePersistenceStrategy 
{

	private final org.hibernate.Session hibernateSession;

	public EntityApplicationStatePersistenceStrategy(Request request, org.hibernate.Session hibernateSession) 
	{
		super(request);
		this.hibernateSession = hibernateSession;
	}

	@SuppressWarnings("unchecked")
	public <T> T get(Class<T> ssoClass, ApplicationStateCreator<T> creator) 
	{
		final Object persistedValue =  getOrCreate(ssoClass, creator);
		
		if(persistedValue instanceof PersistedEntity)
		{
			final PersistedEntity persisted = (PersistedEntity) persistedValue;
			
			Object restored = persisted.restore(this.hibernateSession);
			
			//shall we maybe throw an exception instead?
			if(restored == null)
			{
				set(ssoClass, null);
				return (T) getOrCreate(ssoClass, creator);
			}

			return (T) restored;
		}
		
		return (T) persistedValue;
	}

	public <T> void set(Class<T> ssoClass, T sso) 
	{	
		final String key = buildKey(ssoClass);
		Object entity;
		
		if(sso != null)
		{
			try 
			{
				final String entityName = this.hibernateSession.getEntityName(sso);
				final Serializable id = this.hibernateSession.getIdentifier(sso);
	
				entity = new PersistedEntity(entityName, id);
			} 
			catch (final HibernateException ex) 
			{
				// if entity not attached to a Hibernate Session yet, store it as usual sso
				entity = sso;
			}
		}
		else
		{
			entity = sso;
		}
		
		getSession().setAttribute(key, entity);
	}

}