/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.loader.collection;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.hibernate.FetchMode;
import org.hibernate.LockMode;
import org.hibernate.MappingException;
import org.hibernate.engine.spi.CascadeStyle;
import org.hibernate.engine.spi.LoadQueryInfluencers;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.internal.util.StringHelper;
import org.hibernate.loader.BasicLoader;
import org.hibernate.loader.OuterJoinableAssociation;
import org.hibernate.loader.PropertyPath;
import org.hibernate.persister.collection.QueryableCollection;
import org.hibernate.persister.entity.OuterJoinLoadable;
import org.hibernate.sql.JoinFragment;
import org.hibernate.sql.JoinType;
import org.hibernate.sql.Select;
import org.hibernate.type.AssociationType;

Walker for collections of values and many-to-many associations
Author:Gavin King
See Also:
  • BasicCollectionLoader
/** * Walker for collections of values and many-to-many associations * * @see BasicCollectionLoader * @author Gavin King */
public class BasicCollectionJoinWalker extends CollectionJoinWalker { private final QueryableCollection collectionPersister; public BasicCollectionJoinWalker( QueryableCollection collectionPersister, int batchSize, String subquery, SessionFactoryImplementor factory, LoadQueryInfluencers loadQueryInfluencers) throws MappingException { super( factory, loadQueryInfluencers ); this.collectionPersister = collectionPersister; String alias = generateRootAlias( collectionPersister.getRole() ); walkCollectionTree(collectionPersister, alias); List allAssociations = new ArrayList(); allAssociations.addAll(associations); allAssociations.add( OuterJoinableAssociation.createRoot( collectionPersister.getCollectionType(), alias, getFactory() ) ); initPersisters(allAssociations, LockMode.NONE); initStatementString(alias, batchSize, subquery); } private void initStatementString( final String alias, final int batchSize, final String subquery) throws MappingException { final int joins = countEntityPersisters( associations ); final int collectionJoins = countCollectionPersisters( associations ) + 1; suffixes = BasicLoader.generateSuffixes( joins ); collectionSuffixes = BasicLoader.generateSuffixes( joins, collectionJoins ); StringBuilder whereString = whereString( alias, collectionPersister.getKeyColumnNames(), subquery, batchSize ); String manyToManyOrderBy = ""; String filter = collectionPersister.filterFragment( alias, getLoadQueryInfluencers().getEnabledFilters() ); if ( collectionPersister.isManyToMany() ) { // from the collection of associations, locate OJA for the // ManyToOne corresponding to this persister to fully // define the many-to-many; we need that OJA so that we can // use its alias here // TODO : is there a better way here? Iterator itr = associations.iterator(); AssociationType associationType = ( AssociationType ) collectionPersister.getElementType(); while ( itr.hasNext() ) { OuterJoinableAssociation oja = ( OuterJoinableAssociation ) itr.next(); if ( oja.getJoinableType() == associationType ) { // we found it filter += collectionPersister.getManyToManyFilterFragment( oja.getRHSAlias(), getLoadQueryInfluencers().getEnabledFilters() ); manyToManyOrderBy += collectionPersister.getManyToManyOrderByString( oja.getRHSAlias() ); } } } whereString.insert( 0, StringHelper.moveAndToBeginning( filter ) ); JoinFragment ojf = mergeOuterJoins(associations); Select select = new Select( getDialect() ) .setSelectClause( collectionPersister.selectFragment(alias, collectionSuffixes[0] ) + selectString(associations) ) .setFromClause( collectionPersister.getTableName(), alias ) .setWhereClause( whereString.toString() ) .setOuterJoins( ojf.toFromFragmentString(), ojf.toWhereFragmentString() ); select.setOrderByClause( orderBy( associations, mergeOrderings( collectionPersister.getSQLOrderByString(alias), manyToManyOrderBy ) ) ); if ( getFactory().getSettings().isCommentsEnabled() ) { select.setComment( "load collection " + collectionPersister.getRole() ); } sql = select.toStatementString(); } protected JoinType getJoinType( OuterJoinLoadable persister, PropertyPath path, int propertyNumber, AssociationType associationType, FetchMode metadataFetchMode, CascadeStyle metadataCascadeStyle, String lhsTable, String[] lhsColumns, boolean nullable, int currentDepth) throws MappingException { JoinType joinType = super.getJoinType( persister, path, propertyNumber, associationType, metadataFetchMode, metadataCascadeStyle, lhsTable, lhsColumns, nullable, currentDepth ); //we can use an inner join for the many-to-many if ( joinType==JoinType.LEFT_OUTER_JOIN && path.isRoot() ) { joinType=JoinType.INNER_JOIN; } return joinType; } public String toString() { return getClass().getName() + '(' + collectionPersister.getRole() + ')'; } }