JpaPopulateAssociationsAccessImpl.java

/*
 * Copyright 2007 The Fornax Project Team, including 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.sculptor.framework.accessimpl.jpa;

import java.io.Serializable;
import java.util.Collection;

import javax.persistence.PersistenceException;

import org.apache.commons.beanutils.PropertyUtils;
import org.sculptor.framework.accessapi.PopulateAssociationsAccess;
import org.sculptor.framework.domain.AssociationSpecification;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * <p>
 * Populate the specified associations of a persistent object. Implementation of
 * Access command FindByIdAccess.
 * </p>
 * <p>
 * Command design pattern.
 * </p>
 */
public class JpaPopulateAssociationsAccessImpl<T> extends JpaAccessBase<T> implements PopulateAssociationsAccess<T> {

	private static Logger log = LoggerFactory.getLogger(JpaPopulateAssociationsAccessImpl.class);

	private T entity;
	private AssociationSpecification associationSpecification;
	private T result;

	public JpaPopulateAssociationsAccessImpl(Class<T> persistentClass) {
		setPersistentClass(persistentClass);
	}

	public T getEntity() {
		return entity;
	}

	public void setEntity(T entity) {
		this.entity = entity;
	}

	public AssociationSpecification getAssociationSpecification() {
		return associationSpecification;
	}

	public void setAssociationSpecification(AssociationSpecification associationSpecification) {
		this.associationSpecification = associationSpecification;
	}

	public T getResult() {
		return result;
	}

	public void performExecute() throws PersistenceException {
		result = getEntityManager().find(getPersistentClass(), getId(entity));
		populateAssociations();
	}

	private Serializable getId(Object domainObject) {
		if (PropertyUtils.isReadable(domainObject, "id")) {
			try {
				return (Serializable) PropertyUtils.getProperty(domainObject, "id");
			} catch (Exception e) {
				throw new IllegalArgumentException("Can't get id property of domainObject: " + domainObject);
			}
		} else {
			// no id property, don't know if it is new
			throw new IllegalArgumentException("No id property in domainObject: " + domainObject);
		}
	}

	protected void populateAssociations() {
		if (result == null || associationSpecification == null) {
			return;
		}
		for (String each : associationSpecification.getAssociationNames()) {
			populateAssociation(result, each);
		}
	}

	protected void populateAssociation(Object object, String associationName) {
		try {
			Object association = PropertyUtils.getProperty(object, associationName);
			if (association instanceof Collection<?>) {
				((Collection<?>) association).size();
			} else {
				// TODO is there a more efficient way, something like
				// Hibernate.initialize ?
				// try entityManger.getReference
				String.valueOf(association);
			}
		} catch (Exception e) {
			log.warn("Could not populate association: " + associationName + " for " + object.getClass().getName());
		}
	}

}