HHH-7225 - NullPointerException after persisting null entity value as natural-Id

hibernate-core/src/main/java/org/hibernate/type/EntityType.java

@@ -325,10 +325,13 @@ public abstract class EntityType extends AbstractType implements AssociationType
 		return persister.getIdentifierType().getHashCode( id, factory );
 	}
 
-	/**
-	 * {@inheritDoc}
-	 */
+	@Override
 	public boolean isEqual(Object x, Object y, SessionFactoryImplementor factory) {
+		// associations (many-to-one and one-to-one) can be null...
+		if ( x == null || y == null ) {
+			return x == y;
+		}
+
 		EntityPersister persister = factory.getEntityPersister(associatedEntityName);
 		if ( !persister.canExtractIdOutOfEntity() ) {
 			return super.isEqual(x, y );

hibernate-core/src/matrix/java/org/hibernate/test/naturalid/nullable/A.java

@@ -0,0 +1,57 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * Copyright (c) 2012, 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.test.naturalid.nullable;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.ManyToOne;
+import javax.persistence.OneToMany;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.hibernate.annotations.NaturalId;
+
+/**
+ * @author Guenther Demetz
+ */
+@Entity
+public class A  {
+	@Id
+	@GeneratedValue(strategy = GenerationType.TABLE)
+	public long oid;
+
+	@ManyToOne
+	@NaturalId(mutable=true)
+	public C assC;
+
+	@Column
+	@NaturalId(mutable=true)
+	public String myname;
+
+	@OneToMany(mappedBy="assA")
+	public Set<B> assB = new HashSet<B>();
+}

hibernate-core/src/matrix/java/org/hibernate/test/naturalid/nullable/B.java

@@ -0,0 +1,49 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * Copyright (c) 2012, 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.test.naturalid.nullable;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.ManyToOne;
+
+import org.hibernate.annotations.NaturalId;
+
+/**
+ * @author Guenther Demetz
+ */
+@Entity
+public class B {
+	@Id
+	@GeneratedValue(strategy = GenerationType.TABLE)
+	public long oid;
+
+	@ManyToOne
+	@NaturalId(mutable = true)
+	public A assA = null;
+
+	@NaturalId(mutable = true)
+	public int naturalid;
+}

hibernate-core/src/matrix/java/org/hibernate/test/naturalid/nullable/NullableNaturalIdTest.java

@@ -28,13 +28,16 @@ import org.junit.Test;
 import org.hibernate.Session;
 import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
 
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
 /**
  * @author Steve Ebersole
  */
 public class NullableNaturalIdTest extends BaseCoreFunctionalTestCase {
 	@Override
 	protected Class<?>[] getAnnotatedClasses() {
-		return new Class[] { C.class };
+		return new Class[] { A.class, B.class, C.class };
 	}
 
 	@Test
@@ -53,4 +56,35 @@ public class NullableNaturalIdTest extends BaseCoreFunctionalTestCase {
 		session.getTransaction().commit();
 		session.close();
 	}
+
+	@Test
+	public void testUniqueAssociation() {
+		Session session = openSession();
+		session.beginTransaction();
+		A a = new A();
+		B b = new B();
+		b.naturalid = 100;
+		session.persist( a );
+		session.persist( b ); //b.assA is declared NaturalId, his value is null this moment
+		b.assA = a;
+		a.assB.add( b );
+		session.getTransaction().commit();
+		session.close();
+
+		session = openSession();
+		session.beginTransaction();
+		// this is OK
+		assertNotNull( session.byNaturalId( B.class ).using( "naturalid", 100 ).using( "assA", a ).load() );
+		// this fails, cause EntityType.compare(Object x, Object y) always returns 0 !
+		assertNull( session.byNaturalId( B.class ).using( "naturalid", 100 ).using( "assA", null ).load() );
+		session.getTransaction().commit();
+		session.close();
+
+		session = openSession();
+		session.beginTransaction();
+		session.delete( b );
+		session.delete( a );
+		session.getTransaction().commit();
+		session.close();
+	}
 }