ObjectRetriever.java

/**
 * Copyright (C) 2011  JTalks.org Team
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.jtalks.poulpe.model.dao.hibernate;

import org.hibernate.Session;
import org.jtalks.common.model.entity.Entity;

/**
 * Class for querying the database and retrieving objects already stored there.
 * It is used for ensuring that a sequence of actions in a test leads to
 * expected result - by retrieving an object directly from the database passing
 * any dao instances.
 * 
 * @author Alexey Grigorev
 */
public class ObjectRetriever {

    /**
     * Retrieves the actual object stored in the database, clearing session's
     * cache for ensuring the object is brand new.<br>
     * 
     * The old object is needed here for 1) evicting it from cache 2) getting
     * its id for retrieving.<br>
     * <br>
     * 
     * <b>Example of usage:</b><br>
     * 
     * 1) Retrieving the branch
     * 
     * <pre>
     * private PoulpeBranch retrieveActualBranch() {
     *     return ObjectRetriever.retrieveUpdated(branch, session);
     * }
     * </pre>
     * 
     * 2) Retrieving the section:
     * 
     * <pre>
     * private PoulpeSection retrieveActualSection() {
     *     return ObjectRetriever.retrieveUpdated(section, session);
     * }
     * </pre>
     * 
     * 
     * @param object to retrieve
     * @param session Hibernate session
     * @return brand new retrieved object from the database
     */
    public static <E extends Entity> E retrieveUpdated(E object, Session session) {
        session.evict(object);
        return retrieve(object, session);
    }

    /**
     * Retrieves the actual object stored in the database.<br>
     * <br>
     * 
     * <b>Note</b>: it's not guaranteed that a retrieved object will be
     * retrieved from the database, it may be retrieved from hibernate's cache.
     * Consider using {@link #retrieveUpdated(Entity, Session)} for it clears
     * cache before retrieving.
     * 
     * @param object to retrieve
     * @param session Hibernate session
     */
    @SuppressWarnings("unchecked")
    public static <E extends Entity> E retrieve(E object, Session session) {
        return (E) session.get(object.getClass(), object.getId());
    }

}