001/*******************************************************************************
002 * Copyright 2014 The MITRE Corporation
003 *   and the MIT Kerberos and Internet Trust Consortium
004 * 
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 * 
009 *   http://www.apache.org/licenses/LICENSE-2.0
010 * 
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 ******************************************************************************/
017package org.mitre.util.jpa;
018
019import java.util.List;
020
021import javax.persistence.EntityManager;
022
023/**
024 * @author mfranklin
025 *         Date: 4/28/11
026 *         Time: 2:13 PM
027 */
028public class JpaUtil {
029        public static <T> T getSingleResult(List<T> list) {
030                switch(list.size()) {
031                case 0:
032                        return null;
033                case 1:
034                        return list.get(0);
035                default:
036                        throw new IllegalStateException("Expected single result, got " + list.size());
037                }
038        }
039
040        public static <T, I> T saveOrUpdate(I id, EntityManager entityManager, T entity) {
041                if (id == null) {
042                        entityManager.persist(entity);
043                        entityManager.flush();
044                        return entity;
045                } else {
046                        T tmp = entityManager.merge(entity);
047                        entityManager.flush();
048                        return tmp;
049                }
050        }
051}