HHH-15848 session.isDirty() shouldn't throw exception for transient many-to-one object in a session

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

@@ -175,8 +175,8 @@ public Serializable disassemble(
 			);
 			if ( id == null ) {
 				throw new AssertionFailure(
-						"cannot cache a reference to an object with a null id: " + 
-						getAssociatedEntityName()
+						"cannot cache a reference to an object with a null id: " +
+								getAssociatedEntityName()
 				);
 			}
 			return getIdentifierType( session ).disassemble( id, session, owner );
@@ -207,7 +207,7 @@ public Object assemble(
 			Serializable oid,
 			SharedSessionContractImplementor session,
 			Object owner) throws HibernateException {
-		
+
 		//TODO: currently broken for unique-key references (does not detect
 		//      change to unique key property of the associated object)
 
@@ -245,12 +245,7 @@ public boolean isDirty(
 			Object old,
 			Object current,
 			SharedSessionContractImplementor session) throws HibernateException {
-		if ( isSame( old, current ) ) {
-			return false;
-		}
-		Object oldid = getIdentifier( old, session );
-		Object newid = getIdentifier( current, session );
-		return getIdentifierType( session ).isDirty( oldid, newid, session );
+		return isDirtyManyToOne(old, current, null, session);
 	}
 
 	@Override
@@ -259,18 +254,29 @@ public boolean isDirty(
 			Object current,
 			boolean[] checkable,
 			SharedSessionContractImplementor session) throws HibernateException {
-		if ( isAlwaysDirtyChecked() ) {
-			return isDirty( old, current, session );
+		return isDirtyManyToOne(old, current, isAlwaysDirtyChecked()? null:checkable, session);
+	}
+
+	private boolean isDirtyManyToOne(Object old, Object current, boolean[] checkable, SharedSessionContractImplementor session) {
+		if (isSame(old, current)) {
+			return false;
 		}
-		else {
-			if ( isSame( old, current ) ) {
-				return false;
-			}
-			Object oldid = getIdentifier( old, session );
-			Object newid = getIdentifier( current, session );
-			return getIdentifierType( session ).isDirty( oldid, newid, checkable, session );
+
+		if (old == null || current == null) {
+			return true;
+		}
+
+		if (ForeignKeys.isTransient(getAssociatedEntityName(), current, Boolean.FALSE, session)) {
+			return true;
 		}
-
+
+		Object oldid = getIdentifier(old, session);
+		Object newid = getIdentifier(current, session);
+		Type identifierType = getIdentifierType(session);
+
+		return checkable == null
+				? identifierType.isDirty(oldid, newid, session)
+				: identifierType.isDirty(oldid, newid, checkable, session);
 	}
 
 }

hibernate-core/src/test/java/org/hibernate/orm/test/type/SessionIsDirtyForNewManyToOneObjectTest.java

@@ -0,0 +1,154 @@
+package org.hibernate.orm.test.type;
+
+import jakarta.enterprise.event.Reception;
+import jakarta.persistence.*;
+import org.hibernate.Session;
+import org.hibernate.annotations.Cascade;
+import org.hibernate.annotations.Generated;
+import org.hibernate.engine.spi.SessionFactoryImplementor;
+import org.hibernate.event.PreUpdateEventListenerVetoTest;
+import org.hibernate.event.service.spi.EventListenerRegistry;
+import org.hibernate.event.spi.EventType;
+import org.hibernate.orm.test.legacy.E;
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.orm.junit.BaseSessionFactoryFunctionalTest;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.Before;
+import org.junit.jupiter.api.*;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+@TestForIssue(jiraKey = "HHH-15848")
+public class SessionIsDirtyForNewManyToOneObjectTest extends BaseSessionFactoryFunctionalTest {
+
+    private Long parentId;
+
+    @Override
+    protected Class<?>[] getAnnotatedClasses() {
+        return new Class<?>[] { EntityChild.class, EntityChildAssigned.class, EntityParent.class };
+    }
+
+    @BeforeEach
+    public void setUp() {
+        inTransaction( session -> {
+            EntityChild child = new EntityChild("InitialChild");
+            EntityChildAssigned assigned = new EntityChildAssigned(1L, "InitialChild");
+            EntityParent parent = new EntityParent("InitialParent", child, assigned);
+
+            session.persist(child);
+            session.persist(parent);
+            session.persist(assigned);
+
+
+            session.flush();
+            parentId = parent.id;
+        } );
+    }
+
+    @Test
+    public void SessionIsDirtyShouldNotFailForNewManyToOneObject()
+    {
+        inTransaction( session -> {
+            var parent = getParent(session);
+
+            EntityChild nextChild = new EntityChild("NewManyToOneChild");
+
+            //parent.Child entity is not cascaded, I want to save it explicitly later
+            parent.child = nextChild;
+
+            // will throw TransientObjectException
+            assertDoesNotThrow(()->session.isDirty(), "session.isDirty() call should not fail for transient  many-to-one object referenced in session.\"");
+            assertTrue(session.isDirty(),"session.isDirty() call should return true.");
+
+            session.save(nextChild);
+        });
+    }
+
+    @Test
+    public void SessionIsDirtyShouldNotFailForNewManyToOneObjectWithAssignedId()
+    {
+        inTransaction( session -> {
+            var parent = getParent(session);
+
+            EntityChildAssigned nextChildAssigned = new EntityChildAssigned(2L, "NewManyToOneChildAssignedId");
+
+            //parent.ChildAssigned entity is not cascaded, I want to save it explicitly later
+            parent.childAssigned = nextChildAssigned;
+
+            assertDoesNotThrow(()->session.isDirty(), "session.isDirty() call should not fail for transient  many-to-one object referenced in session.\"");
+            assertTrue(session.isDirty(),"session.isDirty() call should return true.");
+            session.save(nextChildAssigned);
+        });
+    }
+
+    private EntityParent getParent(Session session){
+        return session.get(EntityParent.class, parentId);
+    }
+
+    @AfterEach
+    public void cleanUp() {
+        inTransaction(
+                session -> {
+                    session.createQuery("delete from EntityParent").executeUpdate();
+                    session.createQuery("delete from EntityChild").executeUpdate();
+                    session.createQuery("delete from EntityChildAssigned").executeUpdate();
+                }
+        );
+    }
+
+    @Entity(name = "EntityChild")
+    public static class EntityChild
+    {
+        @Id
+        @GeneratedValue(strategy = GenerationType.AUTO)
+        Long id;
+
+        String name;
+
+        EntityChild(){}
+
+        EntityChild(String name){this.name = name;}
+    }
+
+    @Entity(name = "EntityParent")
+    public static class EntityParent
+    {
+        @Id
+        @GeneratedValue(strategy = GenerationType.AUTO)
+        Long id;
+
+        String name;
+
+        @ManyToOne
+        EntityChild child;
+
+        @ManyToOne
+        EntityChildAssigned childAssigned;
+
+        EntityParent(){}
+
+        EntityParent(String name, EntityChild child, EntityChildAssigned childAssigned){
+            this.name = name;
+            this.child = child;
+            this.childAssigned = childAssigned;
+        }
+    }
+
+    @Entity(name = "EntityChildAssigned")
+    public static class EntityChildAssigned
+    {
+        @Id
+        Long id;
+
+        String name;
+
+        EntityChildAssigned(){}
+
+        EntityChildAssigned(Long id, String name){
+            this.id = id;
+            this.name = name;
+        }
+    }
+}