/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2010, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* 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, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY 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
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.engine.internal;
import java.io.Serializable;
import org.hibernate.EntityMode;
import org.hibernate.HibernateException;
import org.hibernate.TransientObjectException;
import org.hibernate.bytecode.instrumentation.spi.LazyPropertyInitializer;
import org.hibernate.engine.spi.EntityEntry;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.proxy.LazyInitializer;
import org.hibernate.type.CompositeType;
import org.hibernate.type.EntityType;
import org.hibernate.type.Type;
/**
* Algorithms related to foreign key constraint transparency
*
* @author Gavin King
*/
public final class ForeignKeys {
private ForeignKeys() {}
public static class Nullifier {
private final boolean isDelete;
private final boolean isEarlyInsert;
private final SessionImplementor session;
private final Object self;
public Nullifier(Object self, boolean isDelete, boolean isEarlyInsert, SessionImplementor session) {
this.isDelete = isDelete;
this.isEarlyInsert = isEarlyInsert;
this.session = session;
this.self = self;
}
/**
* Nullify all references to entities that have not yet
* been inserted in the database, where the foreign key
* points toward that entity
*/
public void nullifyTransientReferences(final Object[] values, final Type[] types)
throws HibernateException {
for ( int i = 0; i < types.length; i++ ) {
values[i] = nullifyTransientReferences( values[i], types[i] );
}
}
/**
* Return null if the argument is an "unsaved" entity (ie.
* one with no existing database row), or the input argument
* otherwise. This is how Hibernate avoids foreign key constraint
* violations.
*/
private Object nullifyTransientReferences(final Object value, final Type type)
throws HibernateException {
if ( value == null ) {
return null;
}
else if ( type.isEntityType() ) {
EntityType entityType = (EntityType) type;
if ( entityType.isOneToOne() ) {
return value;
}
else {
String entityName = entityType.getAssociatedEntityName();
return isNullifiable(entityName, value) ? null : value;
}
}
else if ( type.isAnyType() ) {
return isNullifiable(null, value) ? null : value;
}
else if ( type.isComponentType() ) {
CompositeType actype = (CompositeType) type;
Object[] subvalues = actype.getPropertyValues(value, session);
Type[] subtypes = actype.getSubtypes();
boolean substitute = false;
for ( int i = 0; i < subvalues.length; i++ ) {
Object replacement = nullifyTransientReferences( subvalues[i], subtypes[i] );
if ( replacement != subvalues[i] ) {
substitute = true;
subvalues[i] = replacement;
}
}
if ( substitute ) {
// todo : need to account for entity mode on the CompositeType interface :(
actype.setPropertyValues( value, subvalues, EntityMode.POJO );
}
return value;
}
else {
return value;
}
}
/**
* Determine if the object already exists in the database,
* using a "best guess"
*/
private boolean isNullifiable(final String entityName, Object object)
throws HibernateException {
if (object==LazyPropertyInitializer.UNFETCHED_PROPERTY) return false; //this is kinda the best we can do...
if ( object instanceof HibernateProxy ) {
// if its an uninitialized proxy it can't be transient
LazyInitializer li = ( (HibernateProxy) object ).getHibernateLazyInitializer();
if ( li.getImplementation(session) == null ) {
return false;
// ie. we never have to null out a reference to
// an uninitialized proxy
}
else {
//unwrap it
object = li.getImplementation();
}
}
// if it was a reference to self, don't need to nullify
// unless we are using native id generation, in which
// case we definitely need to nullify
if ( object == self ) {
return isEarlyInsert || (
isDelete &&
session.getFactory()
.getDialect()
.hasSelfReferentialForeignKeyBug()
);
}
// See if the entity is already bound to this session, if not look at the
// entity identifier and assume that the entity is persistent if the
// id is not "unsaved" (that is, we rely on foreign keys to keep
// database integrity)
EntityEntry entityEntry = session.getPersistenceContext().getEntry(object);
if ( entityEntry==null ) {
return isTransient(entityName, object, null, session);
}
else {
return entityEntry.isNullifiable(isEarlyInsert, session);
}
}
}
/**
* Is this instance persistent or detached?
* If <tt>assumed</tt> is non-null, don't hit the database to make the
* determination, instead assume that value; the client code must be
* prepared to "recover" in the case that this assumed result is incorrect.
*/
public static boolean isNotTransient(String entityName, Object entity, Boolean assumed, SessionImplementor session)
throws HibernateException {
if (entity instanceof HibernateProxy) return true;
if ( session.getPersistenceContext().isEntryFor(entity) ) return true;
return !isTransient(entityName, entity, assumed, session);
}
/**
* Is this instance, which we know is not persistent, actually transient?
* If <tt>assumed</tt> is non-null, don't hit the database to make the
* determination, instead assume that value; the client code must be
* prepared to "recover" in the case that this assumed result is incorrect.
*/
public static boolean isTransient(String entityName, Object entity, Boolean assumed, SessionImplementor session)
throws HibernateException {
if (entity== LazyPropertyInitializer.UNFETCHED_PROPERTY) {
// an unfetched association can only point to
// an entity that already exists in the db
return false;
}
// let the interceptor inspect the instance to decide
Boolean isUnsaved = session.getInterceptor().isTransient(entity);
if (isUnsaved!=null) return isUnsaved.booleanValue();
// let the persister inspect the instance to decide
EntityPersister persister = session.getEntityPersister(entityName, entity);
isUnsaved = persister.isTransient(entity, session);
if (isUnsaved!=null) return isUnsaved.booleanValue();
// we use the assumed value, if there is one, to avoid hitting
// the database
if (assumed!=null) return assumed.booleanValue();
// hit the database, after checking the session cache for a snapshot
Object[] snapshot = session.getPersistenceContext().getDatabaseSnapshot(
persister.getIdentifier( entity, session ),
persister
);
return snapshot==null;
}
/**
* Return the identifier of the persistent or transient object, or throw
* an exception if the instance is "unsaved"
*
* Used by OneToOneType and ManyToOneType to determine what id value should
* be used for an object that may or may not be associated with the session.
* This does a "best guess" using any/all info available to use (not just the
* EntityEntry).
*/
public static Serializable getEntityIdentifierIfNotUnsaved(
final String entityName,
final Object object,
final SessionImplementor session)
throws HibernateException {
if ( object == null ) {
return null;
}
else {
Serializable id = session.getContextEntityIdentifier( object );
if ( id == null ) {
// context-entity-identifier returns null explicitly if the entity
// is not associated with the persistence context; so make some
// deeper checks...
if ( isTransient(entityName, object, Boolean.FALSE, session) ) {
throw new TransientObjectException(
"object references an unsaved transient instance - save the transient instance before flushing: " +
(entityName == null ? session.guessEntityName( object ) : entityName)
);
}
id = session.getEntityPersister( entityName, object ).getIdentifier( object, session );
}
return id;
}
}
}