//$Id: BasicCollectionJoinWalker.java 9875 2006-05-04 16:23:44Z steve.ebersole@jboss.com $
package org.hibernate.loader.collection;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.hibernate.FetchMode;
import org.hibernate.LockMode;
import org.hibernate.MappingException;
import org.hibernate.engine.SessionFactoryImplementor;
import org.hibernate.loader.BasicLoader;
import org.hibernate.loader.OuterJoinableAssociation;
import org.hibernate.persister.collection.QueryableCollection;
import org.hibernate.sql.JoinFragment;
import org.hibernate.sql.Select;
import org.hibernate.type.AssociationType;
import org.hibernate.util.CollectionHelper;
import org.hibernate.util.StringHelper;
/**
* 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,
Map enabledFilters)
throws MappingException {
super(factory, enabledFilters);
this.collectionPersister = collectionPersister;
String alias = generateRootAlias( collectionPersister.getRole() );
walkCollectionTree(collectionPersister, alias);
List allAssociations = new ArrayList();
allAssociations.addAll(associations);
allAssociations.add( new OuterJoinableAssociation(
collectionPersister.getCollectionType(),
null,
null,
alias,
JoinFragment.LEFT_OUTER_JOIN,
getFactory(),
CollectionHelper.EMPTY_MAP
) );
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 );
StringBuffer whereString = whereString(
alias,
collectionPersister.getKeyColumnNames(),
subquery,
batchSize
);
String manyToManyOrderBy = "";
String filter = collectionPersister.filterFragment( alias, 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(),
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();
}
/**
* We can use an inner join for first many-to-many association
*/
protected int getJoinType(
AssociationType type,
FetchMode config,
String path,
Set visitedAssociations,
String lhsTable,
String[] lhsColumns,
boolean nullable,
int currentDepth)
throws MappingException {
int joinType = super.getJoinType(
type,
config,
path,
lhsTable,
lhsColumns,
nullable,
currentDepth,
null
);
//we can use an inner join for the many-to-many
if ( joinType==JoinFragment.LEFT_OUTER_JOIN && "".equals(path) ) {
joinType=JoinFragment.INNER_JOIN;
}
return joinType;
}
public String toString() {
return getClass().getName() + '(' + collectionPersister.getRole() + ')';
}
}