JPAListModel.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.jpa;

import java.util.List;

import javax.persistence.EntityManager;

import net.databinder.jpa.Databinder;

import org.apache.wicket.model.LoadableDetachableModel;

/**
 * Model for a List generated by a JPA query. This read-only model can be used
 * to fill ListModel and PropertyListModel components with rows from a database.
 *
 * @param <T> Object list generic parameter
 *
 * @author rhansen@kindleit.net
 */
public class JPAListModel<T> extends LoadableDetachableModel<List<T>> {

  private static final long serialVersionUID = 8178717667562698158L;

  private QueryBuilder queryBuilder;

	private String factoryKey;

	/**
	 * Contructor for a simple query.
	 * @param queryString query with no parameters
	 */
	public JPAListModel(final String queryString) {
		this(new QueryBinderBuilder(queryString));
	}

	/**
	 * Constructor for a parameterized query.
	 * @param queryString Query with parameters
	 * @param queryBinder object that binds the query parameters
	 */
	public JPAListModel(final String queryString, final QueryBinder queryBinder) {
		this(new QueryBinderBuilder(queryString, queryBinder));
	}

	/**
	 * Constructor for a list of all results in class. While this query will be too open for
	 * most applications, it can useful in early development.
	 * @param objectClass class objects to return
	 */
	public JPAListModel(final Class<T> objectClass) {
		this(new QueryBinderBuilder("from " + objectClass.getCanonicalName()));
	}

	/**
	 * Constructor for a custom query that is built by the calling application.
	 * @param queryBuilder builder to create and bind query object
	 */
	public JPAListModel(final QueryBuilder queryBuilder) {
		this.queryBuilder = queryBuilder;
	}

	/** @return session factory key, or null for the default factory */
	public Object getFactoryKey() {
		return factoryKey;
	}

	/**
	 * Set a factory key other than the default (null).
	 * @param key session factory key
	 * @return this, for chaining
	 */
	public JPAListModel<T> setFactoryKey(final String key) {
		this.factoryKey = key;
		return this;
	}

	/**
	 * Load the object List through Hibernate, binding query parameters if available.
	 */
	@SuppressWarnings("unchecked")
	@Override
	protected List<T> load() {
		final EntityManager em = Databinder.getEntityManager(factoryKey);
  	return queryBuilder.build(em).getResultList();
	}
}