/*
 * Copyright (c) 2009-2010 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;

import java.util.List;

import javax.persistence.Query;

import org.eurekastreams.commons.model.DomainEntity;
import org.eurekastreams.server.persistence.mappers.requests.FindByIdRequest;

/**
 * Mapper used for finding DomainEntities by id.
 *
 * @param <TDomainEntityType>
 *            Type of DomainEntity.
 */
@SuppressWarnings("unchecked")
public class FindByIdMapper<TDomainEntityType extends DomainEntity> extends
        ReadMapper<FindByIdRequest, TDomainEntityType>
{
    /**
     * Finds a DomainEntity by ID.
     *
     * @param inRequest
     *            The MapperRequest.
     * @return the requested domain entity. Returns null if no results.
     */
    public TDomainEntityType execute(final FindByIdRequest inRequest)
    {
        Query q = getEntityManager().createQuery("from " + inRequest.getEntityName() + " where id = :domainEntityId")
                .setParameter("domainEntityId", inRequest.getEntityId());

        List<TDomainEntityType> results = q.getResultList();
        if (!results.isEmpty() && results.size() == 1)
        {
            return results.get(0);
        }
        else
        {
            return null;
        }
    }
}