/*
* Copyright (c) 2011 Lockheed Martin Corporation
*
* 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.eurekastreams.server.persistence.mappers.db;
import org.apache.commons.logging.Log;
import org.eurekastreams.commons.logging.LogFactory;
import org.eurekastreams.server.domain.stream.plugins.FeedSubscriber;
import org.eurekastreams.server.persistence.mappers.BaseArgDomainMapper;
/**
* Deletes a FeedSubscriber, deleting the Feed as well, if there are no more subscribers.
*/
public class DeleteFeedSubscriberMapper extends BaseArgDomainMapper<Long, Boolean>
{
/**
* Logger.
*/
private Log log = LogFactory.make();
/**
* Delete the FeedSubscriber, also deleting the Feed if there are no more subscribers to it.
*
* @param inFeedSubscriberId
* the ID of the FeedSubscriber to delete
* @return true
*/
@Override
public Boolean execute(final Long inFeedSubscriberId)
{
Long feedId;
FeedSubscriber subscriber;
// get the feed
subscriber = (FeedSubscriber) getEntityManager().createQuery("FROM FeedSubscriber WHERE id = :id")
.setParameter("id", inFeedSubscriberId).getSingleResult();
feedId = subscriber.getFeed().getId();
getEntityManager().remove(subscriber);
getEntityManager().flush();
// see if the feed has no subscribers - if so, delete it
Long subscriberCount = (Long) getEntityManager()
.createQuery("SELECT COUNT(elements(feedSubscribers)) FROM Feed WHERE id = :id")
.setParameter("id", feedId).getSingleResult();
if (subscriberCount == 0)
{
log.info("Deleting feed - no more subscribers - id: " + feedId);
getEntityManager().createQuery("DELETE FROM Feed WHERE id = :id").setParameter("id", feedId)
.executeUpdate();
getEntityManager().flush();
}
return Boolean.TRUE;
}
}