DataObjectModel.java

/*
 * Databinder: a simple bridge from Wicket to Hibernate
 * Copyright (C) 2006  Nathan Hamblen nathan@technically.us

 * 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 St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package net.databinder.models.cay;

import net.databinder.cay.Databinder;
import net.databinder.models.BindingModel;
import net.databinder.models.LoadableWritableModel;

import org.apache.cayenne.DataObject;
import org.apache.cayenne.DataObjectUtils;
import org.apache.cayenne.ObjectId;
import org.apache.cayenne.PersistenceState;

/**
 * Basic model mapping to a single Cayenne data object. Detaches at the end
 * of a request *unless* the object has uncommitted changes.
 **/
public class DataObjectModel<T extends DataObject> extends LoadableWritableModel<T> implements BindingModel<T> {
	
	private ObjectId id;
	private T retainedObject;

	@SuppressWarnings("unchecked")
	public DataObjectModel(Class<T> objectClass) {
		setObject((T) Databinder.getContext().newObject(objectClass));
	}
	
	public DataObjectModel(ObjectId id) {
		this.id = id;
	}

	public DataObjectModel(DataObject object) {
		id = object.getObjectId();
	}

	/** Loads from storage unless the object has been retained. */
	@SuppressWarnings("unchecked")
	@Override
	protected T load() {
		if (retainedObject != null) {
			Databinder.getContext().registerNewObject(retainedObject);
			return retainedObject;
		}
		return (T) DataObjectUtils.objectForPK(Databinder.getContext(), id);
	}

	/**
	 * @param object must be a Cayenne DataObject
	 */
	public void setObject(T dataObject) {
		id = dataObject.getObjectId();
		setTempModelObject(dataObject);
		if (!isBound())
			retainedObject = dataObject;
		else
			retainedObject = null;
	}
	
	@Override
	public T getObject() {
		return super.getObject();
	}
	
	/**
	 * Detaches any retained object that is fully commited to storage.
	 */
	@Override
	protected void onDetach() {
		if (retainedObject != null) {
			id = retainedObject.getObjectId();
			if (retainedObject.getPersistenceState() == PersistenceState.COMMITTED)
				retainedObject = null;
		}
	}
	
	public boolean isBound() {
		return !id.isTemporary();
	}
	
	@SuppressWarnings("unchecked")
	public void unbind() {
		setObject((T) Databinder.getContext().createAndRegisterNewObject(id.getEntityName()));
	}

}