Hibernate example source code file (SubqueryExpression.java)

This example Hibernate source code file (SubqueryExpression.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

criteriaimpl, criteriaimpl, criteriaquery, criteriaquery, criteriaquerytranslator, hibernateexception, sessionfactoryimplementor, sessionfactoryimplementor, string, string, stringbuffer, subqueryexpression, type, typedvalue

The Hibernate SubqueryExpression.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program 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 distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 *
 */
package org.hibernate.criterion;
import org.hibernate.Criteria;
import org.hibernate.EntityMode;
import org.hibernate.HibernateException;
import org.hibernate.engine.spi.QueryParameters;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.engine.spi.TypedValue;
import org.hibernate.internal.CriteriaImpl;
import org.hibernate.loader.criteria.CriteriaJoinWalker;
import org.hibernate.loader.criteria.CriteriaQueryTranslator;
import org.hibernate.persister.entity.OuterJoinLoadable;
import org.hibernate.type.Type;

/**
 * @author Gavin King
 */
public abstract class SubqueryExpression implements Criterion {
	
	private CriteriaImpl criteriaImpl;
	private String quantifier;
	private String op;
	private QueryParameters params;
	private Type[] types;
	private CriteriaQueryTranslator innerQuery;

	protected Type[] getTypes() {
		return types;
	}
	
	protected SubqueryExpression(String op, String quantifier, DetachedCriteria dc) {
		this.criteriaImpl = dc.getCriteriaImpl();
		this.quantifier = quantifier;
		this.op = op;
	}
	
	protected abstract String toLeftSqlString(Criteria criteria, CriteriaQuery outerQuery);

	public String toSqlString(Criteria criteria, CriteriaQuery criteriaQuery) throws HibernateException {
		final SessionFactoryImplementor factory = criteriaQuery.getFactory();
		final OuterJoinLoadable persister =
				( OuterJoinLoadable ) factory.getEntityPersister( criteriaImpl.getEntityOrClassName() );

		createAndSetInnerQuery( criteriaQuery, factory );
		criteriaImpl.setSession( deriveRootSession( criteria ) );

		CriteriaJoinWalker walker = new CriteriaJoinWalker(
				persister,
				innerQuery,
				factory,
				criteriaImpl,
				criteriaImpl.getEntityOrClassName(),
				criteriaImpl.getSession().getLoadQueryInfluencers(),
				innerQuery.getRootSQLALias()
		);

		String sql = walker.getSQLString();

		final StringBuffer buf = new StringBuffer( toLeftSqlString(criteria, criteriaQuery) );
		if ( op != null ) {
			buf.append( ' ' ).append( op ).append( ' ' );
		}
		if ( quantifier != null ) {
			buf.append( quantifier ).append( ' ' );
		}
		return buf.append( '(' ).append( sql ).append( ')' )
				.toString();
	}

	private SessionImplementor deriveRootSession(Criteria criteria) {
		if ( criteria instanceof CriteriaImpl ) {
			return ( ( CriteriaImpl ) criteria ).getSession();
		}
		else if ( criteria instanceof CriteriaImpl.Subcriteria ) {
			return deriveRootSession( ( ( CriteriaImpl.Subcriteria ) criteria ).getParent() );
		}
		else {
			// could happen for custom Criteria impls.  Not likely, but...
			// 		for long term solution, see HHH-3514
			return null;
		}
	}

	public TypedValue[] getTypedValues(Criteria criteria, CriteriaQuery criteriaQuery) 
	throws HibernateException {
		//the following two lines were added to ensure that this.params is not null, which
		//can happen with two-deep nested subqueries
		SessionFactoryImplementor factory = criteriaQuery.getFactory();
		createAndSetInnerQuery(criteriaQuery, factory);
		
		Type[] ppTypes = params.getPositionalParameterTypes();
		Object[] ppValues = params.getPositionalParameterValues();
		TypedValue[] tv = new TypedValue[ppTypes.length];
		for ( int i=0; i<ppTypes.length; i++ ) {
			tv[i] = new TypedValue( ppTypes[i], ppValues[i], EntityMode.POJO );
		}
		return tv;
	}

	/**
	 * Creates the inner query used to extract some useful information about types, since it is needed in both methods.
	 *
	 * @param criteriaQuery The criteria query
	 * @param factory The session factory.
	 */
	private void createAndSetInnerQuery(CriteriaQuery criteriaQuery, SessionFactoryImplementor factory) {
		if ( innerQuery == null ) {
			//with two-deep subqueries, the same alias would get generated for
			//both using the old method (criteriaQuery.generateSQLAlias()), so
			//that is now used as a fallback if the main criteria alias isn't set
			String alias;
			if ( this.criteriaImpl.getAlias() == null ) {
				alias = criteriaQuery.generateSQLAlias();
			}
			else {
				alias = this.criteriaImpl.getAlias() + "_";
			}

			innerQuery = new CriteriaQueryTranslator(
					factory,
					criteriaImpl,
					criteriaImpl.getEntityOrClassName(), //implicit polymorphism not supported (would need a union)
					alias,
					criteriaQuery
				);

			params = innerQuery.getQueryParameters();
			types = innerQuery.getProjectedTypes();
		}
	}
}