/*
* Hibernate OGM, Domain model persistence for NoSQL datastores
*
* 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.ogm.hibernatecore.impl;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.hibernate.HibernateException;
import org.hibernate.LockOptions;
import org.hibernate.engine.spi.QueryParameters;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.loader.custom.CustomLoader;
import org.hibernate.loader.custom.Return;
import org.hibernate.loader.custom.RootReturn;
import org.hibernate.ogm.datastore.spi.Tuple;
import org.hibernate.ogm.dialect.GridDialect;
import org.hibernate.ogm.grid.EntityKeyMetadata;
import org.hibernate.ogm.loader.OgmLoader;
import org.hibernate.ogm.loader.OgmLoadingContext;
import org.hibernate.ogm.loader.nativeloader.BackendCustomQuery;
import org.hibernate.ogm.persister.OgmEntityPersister;
import org.hibernate.ogm.util.ClosableIterator;
import org.hibernate.persister.entity.Loadable;
import org.hibernate.service.Service;
import org.hibernate.service.spi.ServiceRegistryImplementor;
import org.hibernate.type.Type;
/**
* Extension point for a loader that executes native NoSQL queries.
*
* @author Davide D'Alto <davide@hibernate.org>
*/
public class BackendCustomLoader extends CustomLoader {
private final BackendCustomQuery customQuery;
public BackendCustomLoader(BackendCustomQuery customQuery, SessionFactoryImplementor factory) {
super( customQuery, factory );
this.customQuery = customQuery;
}
/**
* Whether this query is a selection of a complete entity or not. Queries mixing scalar values and entire entities
* in one result are not supported atm.
*/
private boolean isEntityQuery() {
for ( Return queryReturn : customQuery.getCustomQueryReturns() ) {
if ( queryReturn instanceof RootReturn ) {
return true;
}
}
return false;
}
@Override
protected List<?> list(SessionImplementor session, QueryParameters queryParameters, Set querySpaces, Type[] resultTypes) throws HibernateException {
ClosableIterator<Tuple> tuples = executeQuery( session, service( session, GridDialect.class ), queryParameters, resultTypes );
try {
if ( isEntityQuery() ) {
return listOfEntities( session, resultTypes, tuples );
}
else {
return listOfArrays( tuples );
}
}
finally {
tuples.close();
}
}
// At the moment we only support the case where one entity type is returned
private List<Object> listOfEntities(SessionImplementor session, Type[] resultTypes, ClosableIterator<Tuple> tuples) {
List<Object> results = new ArrayList<Object>();
Class<?> returnedClass = resultTypes[0].getReturnedClass();
while ( tuples.hasNext() ) {
Tuple tuple = tuples.next();
OgmLoader loader = createLoader( session, returnedClass );
results.add( entity( session, tuple, loader ) );
}
return results;
}
private List<Object> listOfArrays(Iterator<Tuple> tuples) {
List<Object> results = new ArrayList<Object>();
while ( tuples.hasNext() ) {
Tuple tuple = tuples.next();
Object[] entry = new Object[tuple.getColumnNames().size()];
int i = 0;
for ( String column : tuple.getColumnNames() ) {
entry[i++] = tuple.get( column );
}
results.add( entry );
}
return results;
}
private ClosableIterator<Tuple> executeQuery(SessionImplementor session, GridDialect dialect, QueryParameters queryParameters , Type[] resultTypes) {
Loadable[] entityPersisters = getEntityPersisters();
EntityKeyMetadata[] metadatas = new EntityKeyMetadata[entityPersisters.length];
for ( int i = 0; i < metadatas.length; i++ ) {
metadatas[i] = metadata( session.getFactory(), resultTypes[i] );
}
return dialect.executeBackendQuery( customQuery, queryParameters, metadatas );
}
private <T extends Service> T service(SessionImplementor session, Class<T> serviceRole) {
return serviceRegistry( session ).getService( serviceRole );
}
private ServiceRegistryImplementor serviceRegistry(SessionImplementor session) {
return session.getFactory().getServiceRegistry();
}
private <T> T entity(SessionImplementor session, Tuple tuple, OgmLoader loader) {
OgmLoadingContext ogmLoadingContext = new OgmLoadingContext();
ogmLoadingContext.setTuples( Arrays.asList( tuple ) );
@SuppressWarnings("unchecked")
List<T> entities = (List<T>) loader.loadEntities( session, LockOptions.NONE, ogmLoadingContext );
return entities.get( 0 );
}
private OgmLoader createLoader(SessionImplementor session, Class<?> entityClass) {
OgmEntityPersister persister = (OgmEntityPersister) ( session.getFactory() ).getEntityPersister( entityClass.getName() );
OgmLoader loader = new OgmLoader( new OgmEntityPersister[] { persister } );
return loader;
}
private EntityKeyMetadata metadata(SessionFactoryImplementor sessionFactory, Type resultType) {
OgmEntityPersister persister = (OgmEntityPersister) ( sessionFactory ).getEntityPersister( resultType.getName() );
return new EntityKeyMetadata( persister.getTableName(), persister.getRootTableIdentifierColumnNames() );
}
}