/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* JBoss, Home of Professional Open Source
* Copyright 2013 Red Hat Inc. and/or its affiliates and other contributors
* as indicated by the @authors tag. All rights reserved.
* See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* 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, v. 2.1.
* This program is distributed in the hope that it will be useful, but WITHOUT A
* 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,
* v.2.1 along with this distribution; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
package org.hibernate.engine.query.spi;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import javax.persistence.AttributeNode;
import javax.persistence.EntityGraph;
import javax.persistence.Subgraph;
import org.hibernate.QueryException;
import org.hibernate.engine.internal.JoinSequence;
import org.hibernate.hql.internal.ast.HqlSqlWalker;
import org.hibernate.hql.internal.ast.tree.FromClause;
import org.hibernate.hql.internal.ast.tree.FromElement;
import org.hibernate.hql.internal.ast.tree.FromElementFactory;
import org.hibernate.persister.collection.QueryableCollection;
import org.hibernate.sql.JoinType;
import org.hibernate.type.EntityType;
import org.hibernate.type.Type;
/**
* Encapsulates a JPA EntityGraph provided through a JPQL query hint. Converts the fetches into a list of AST
* FromElements. The logic is kept here as much as possible in order to make it easy to remove this in the future,
* once our AST is improved and this "hack" is no longer needed.
*
* @author Brett Meyer
*/
public class EntityGraphQueryHint {
private final EntityGraph<?> originEntityGraph;
public EntityGraphQueryHint( EntityGraph<?> originEntityGraph ) {
this.originEntityGraph = originEntityGraph;
}
public List<FromElement> toFromElements(FromClause fromClause, HqlSqlWalker walker) {
// If a role already has an explicit fetch in the query, skip it in the graph.
Map<String, FromElement> explicitFetches = new HashMap<String, FromElement>();
Iterator iter = fromClause.getFromElements().iterator();
while ( iter.hasNext() ) {
final FromElement fromElement = ( FromElement ) iter.next();
if (fromElement.getRole() != null) {
explicitFetches.put( fromElement.getRole(), fromElement );
}
}
return getFromElements(
originEntityGraph.getAttributeNodes(),
fromClause.getFromElement(),
fromClause,
walker,
explicitFetches
);
}
private List<FromElement> getFromElements(
List attributeNodes,
FromElement origin,
FromClause fromClause,
HqlSqlWalker walker,
Map<String, FromElement> explicitFetches) {
final List<FromElement> fromElements = new ArrayList<FromElement>();
for (Object obj : attributeNodes) {
final AttributeNode<?> attributeNode = (AttributeNode<?>) obj;
final String attributeName = attributeNode.getAttributeName();
final String className = origin.getClassName();
final String role = className + "." + attributeName;
final String classAlias = origin.getClassAlias();
final String originTableAlias = origin.getTableAlias();
Type propertyType = origin.getPropertyType( attributeName, attributeName );
try {
FromElement fromElement = null;
if (!explicitFetches.containsKey( role )) {
if ( propertyType.isEntityType() ) {
final EntityType entityType = (EntityType) propertyType;
final String[] columns = origin.toColumns( originTableAlias, attributeName, false );
final String tableAlias = walker.getAliasGenerator().createName(
entityType.getAssociatedEntityName() );
final FromElementFactory fromElementFactory = new FromElementFactory( fromClause, origin,
attributeName, classAlias, columns, false);
final JoinSequence joinSequence = walker.getSessionFactoryHelper().createJoinSequence(
false, entityType, tableAlias, JoinType.LEFT_OUTER_JOIN, columns );
fromElement = fromElementFactory.createEntityJoin(
entityType.getAssociatedEntityName(),
tableAlias,
joinSequence,
true,
walker.isInFrom(),
entityType,
role,
null
);
}
else if ( propertyType.isCollectionType() ) {
final String[] columns = origin.toColumns( originTableAlias, attributeName, false );
final FromElementFactory fromElementFactory = new FromElementFactory( fromClause, origin,
attributeName, classAlias, columns, false);
final QueryableCollection queryableCollection = walker.getSessionFactoryHelper()
.requireQueryableCollection( role );
fromElement = fromElementFactory.createCollection(
queryableCollection, role, JoinType.LEFT_OUTER_JOIN, true, false ) ;
}
}
if (fromElement != null) {
fromElements.add( fromElement );
// recurse into subgraphs
for (Subgraph<?> subgraph : attributeNode.getSubgraphs().values()) {
fromElements.addAll( getFromElements( subgraph.getAttributeNodes(), fromElement,
fromClause, walker, explicitFetches ) );
}
}
}
catch (Exception e) {
throw new QueryException( "Could not apply the EntityGraph to the Query!", e );
}
}
return fromElements;
}
}