/*
* 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.io.Serializable;
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.CustomQuery;
import org.hibernate.loader.custom.Return;
import org.hibernate.loader.custom.RootReturn;
import org.hibernate.loader.custom.ScalarReturn;
import org.hibernate.ogm.dialect.query.spi.BackendQuery;
import org.hibernate.ogm.dialect.query.spi.ClosableIterator;
import org.hibernate.ogm.dialect.query.spi.QueryableGridDialect;
import org.hibernate.ogm.loader.impl.OgmLoader;
import org.hibernate.ogm.loader.impl.OgmLoadingContext;
import org.hibernate.ogm.loader.nativeloader.impl.BackendCustomQuery;
import org.hibernate.ogm.model.spi.Tuple;
import org.hibernate.ogm.persister.impl.OgmEntityPersister;
import org.hibernate.ogm.type.spi.GridType;
import org.hibernate.ogm.type.spi.TypeTranslator;
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 CustomQuery customQuery;
private final TypeTranslator typeTranslator;
private final BackendCustomLoaderContext<?> loaderContext;
public BackendCustomLoader(BackendCustomQuery<?> customQuery, SessionFactoryImplementor factory) {
super( customQuery, factory );
this.customQuery = customQuery;
this.typeTranslator = factory.getServiceRegistry().getService( TypeTranslator.class );
this.loaderContext = getLoaderContext( customQuery, factory );
}
@Override
public Set<String> getQuerySpaces() {
@SuppressWarnings("unchecked")
Set<String> querySpaces = super.getQuerySpaces();
return querySpaces;
}
private static <T extends Serializable> BackendCustomLoaderContext<T> getLoaderContext(BackendCustomQuery<T> customQuery, SessionFactoryImplementor factory) {
@SuppressWarnings("unchecked")
QueryableGridDialect<T> gridDialect = factory.getServiceRegistry().getService( QueryableGridDialect.class );
return new BackendCustomLoaderContext<T>( gridDialect, 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 = loaderContext.executeQuery( queryParameters );
try {
if ( isEntityQuery() ) {
return listOfEntities( session, resultTypes, tuples );
}
else {
return listOfArrays( session, 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(SessionImplementor session, Iterator<Tuple> tuples) {
List<Object> results = new ArrayList<Object>();
while ( tuples.hasNext() ) {
Tuple tuple = tuples.next();
Object[] entry = null;
if ( !customQuery.getCustomQueryReturns().isEmpty() ) {
entry = new Object[customQuery.getCustomQueryReturns().size()];
int i = 0;
for ( Return queryReturn : customQuery.getCustomQueryReturns() ) {
ScalarReturn scalarReturn = (ScalarReturn) queryReturn;
Type type = scalarReturn.getType();
if ( type != null ) {
GridType gridType = typeTranslator.getType( type );
entry[i++] = gridType.nullSafeGet( tuple, scalarReturn.getColumnAlias(), session, null );
}
else {
entry[i++] = tuple.get( scalarReturn.getColumnAlias() );
}
}
}
else {
// TODO OGM-564 As a temporary work-around, retrieving the names from the actual result in case there
// are no query returns defined (no result mapping has been given for a native query). Actually we
// should drive this based on the selected columns as otherwise the order might not be correct and/or
// null values will not show up
entry = new Object[tuple.getColumnNames().size()];
int i = 0;
for ( String column : tuple.getColumnNames() ) {
entry[i++] = tuple.get( column );
}
}
if ( entry.length == 1 ) {
results.add( entry[0] );
}
else {
results.add( entry );
}
}
return results;
}
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;
}
/**
* Extracted as separate class for the sole purpose of capturing the type parameter {@code T} without exposing it to
* the callers which don't actually need it.
*
* @author Gunnar Morling
*/
private static class BackendCustomLoaderContext<T extends Serializable> {
private final QueryableGridDialect<T> gridDialect;
private final BackendQuery<T> query;
public BackendCustomLoaderContext(QueryableGridDialect<T> gridDialect, BackendCustomQuery<T> customQuery) {
this.gridDialect = gridDialect;
this.query = new BackendQuery<T>(
customQuery.getQueryObject(),
customQuery.getSingleEntityKeyMetadataOrNull()
);
}
public ClosableIterator<Tuple> executeQuery(QueryParameters queryParameters) {
return gridDialect.executeBackendQuery( query, queryParameters );
}
}
}