org.springframework.orm.hibernate3.support.IdTransferringMergeEventListener Maven / Gradle / Ivy
/*
* Copyright 2002-2005 the original author or authors.
*
* 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.springframework.orm.hibernate3.support;
import java.io.Serializable;
import java.util.Map;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.event.MergeEvent;
import org.hibernate.event.def.DefaultMergeEventListener;
import org.hibernate.persister.entity.EntityPersister;
/**
* Extension of Hibernate's DefaultMergeEventListener, transferring the ids
* of newly saved objects to the corresponding original objects (that are part
* of the detached object graph passed into the merge method).
*
* Transferring newly assigned ids to the original graph allows for continuing
* to use the original object graph, despite merged copies being registered with
* the current Hibernate Session. This is particularly useful for web applications
* that might want to store an object graph and then render it in a web view,
* with links that include the id of certain (potentially newly saved) objects.
*
*
The merge behavior given by this MergeEventListener is nearly identical
* to TopLink's merge behavior. See PetClinic for an example, which relies on
* ids being available for newly saved objects: the HibernateClinic
* and TopLinkClinic DAO implementations both use straight merge
* calls, with the Hibernate SessionFactory configuration specifying an
* IdTransferringMergeEventListener.
*
*
Typically specified as entry for LocalSessionFactoryBean's "eventListeners"
* map, with key "merge".
*
*
NOTE: Due to incompatible changes in the Hibernate 3.1 event listener
* API, this merge event listener will only work as-is with Hibernate 3.1+. Consider
* copying this implementation and adapting it to the older API if you want to run
* it against Hibernate 3.0.
*
* @author Juergen Hoeller
* @since 1.2
* @see org.springframework.orm.hibernate3.LocalSessionFactoryBean#setEventListeners(java.util.Map)
*/
public class IdTransferringMergeEventListener extends DefaultMergeEventListener {
/**
* Hibernate 3.1 implementation of ID transferral.
* Comment this out and the below in for a Hibernate 3.0 version of this class.
*/
protected void entityIsTransient(MergeEvent event, Map copyCache) {
super.entityIsTransient(event, copyCache);
SessionImplementor session = event.getSession();
EntityPersister persister = session.getEntityPersister(event.getEntityName(), event.getEntity());
// Extract id from merged copy (which is currently registered with Session).
Serializable id = persister.getIdentifier(event.getResult(), session.getEntityMode());
// Set id on original object (which remains detached).
persister.setIdentifier(event.getOriginal(), id, session.getEntityMode());
}
/**
* Hibernate 3.0 implementation of ID transferral.
* Comment this in and the above out for a Hibernate 3.0 version of this class.
*/
/*
protected Object entityIsTransient(MergeEvent event, Map copyCache) {
Object mergedCopy = super.entityIsTransient(event, copyCache);
SessionImplementor session = event.getSession();
EntityPersister persister = session.getEntityPersister(event.getEntityName(), event.getEntity());
// Extract id from merged copy (which is currently registered with Session).
Serializable id = persister.getIdentifier(mergedCopy, session.getEntityMode());
// Set id on original object (which remains detached).
persister.setIdentifier(event.getOriginal(), id, session.getEntityMode());
return mergedCopy;
}
*/
}