#1496 Fix ManyToOneType.IsModified to handle both object instance and identifier passed to the parameter “old”.

The tests "EventListener_Entity_ChangeProperty" and "EventListener_EntityWithCompositeId_ChangeProperty" fail for current code in ManyToOneType.IsModified(…) where "old" parameter is not parsed.

The tests "SelectBeforeUpdate_EntityWithCompositeId_ChangeProperty" and "SelectBeforeUpdate_ManyToOneWithCompositeId_ChangeProperty" fail
 if we apply Hibernate fix HHH-3730 "(var oldIdentifier =GetIdentifier(old, session))"

All tests pass if we apply proposed fix: "var oldIdentifier = IsIdentifier(old, session) ? old : GetIdentifier(old, session);"

I added extra tests to see what data hit the ManyToOneType.IsModified(…). We can leave just 4 tests listed above and remove or set to [Ignore] others.

ManyToOneType.IsModifiedAsync(...) could be fixed same way but would like to hear the feedback on the issue and proposed solution first.

Author: Misha Urubkov

src/NHibernate.Test/NHSpecificTest/GH1496/AuditEventListener.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using NHibernate.Event;
+
+namespace NHibernate.Test.NHSpecificTest.GH1496
+{
+	public class AuditEventListener : IPostUpdateEventListener
+	{
+		public IList<Item> ModifiedItems { get; set; } = new List<Item>();
+		private bool isActive = false;
+
+		public void Start()
+		{
+			ModifiedItems.Clear();
+			isActive = true;
+		}
+
+		public void Stop()
+		{
+			isActive = false;
+		}
+
+		public Task OnPostUpdateAsync(PostUpdateEvent @event, CancellationToken cancellationToken)
+		{
+			throw new NotImplementedException();
+		}
+
+		public void OnPostUpdate(PostUpdateEvent @event)
+		{
+			if (isActive == false)
+			{ return; }
+
+			var modifiedItems = @event.Persister.FindModified(@event.OldState, @event.State, @event.Entity, @event.Session);
+			foreach (int index in modifiedItems)
+			{
+				ModifiedItems.Add(new Item
+				{
+					Index = index,
+					OldState = @event.OldState[index],
+					State = @event.State[index]
+				});
+			}
+		}
+
+		public class Item
+		{
+			public int Index { get; set; }
+			public object OldState { get; set; }
+			public object State { get; set; }
+		}
+
+	}
+
+
+}

src/NHibernate.Test/NHSpecificTest/GH1496/Entities.cs

@@ -0,0 +1,129 @@
+using System;
+
+
+namespace NHibernate.Test.NHSpecificTest.GH1496
+{
+	// Entity with ManyToOne type (Address) with regular (int) Id
+	public class Person
+	{
+		public virtual int Id { get; set; }
+
+		public virtual string Name { get; set; }
+
+		public virtual Address Address { get; set; }
+
+		public Person()
+		{
+		}
+
+		public Person(int id, string name, Address address)
+		{
+			Id = id;
+			Name = name;
+			Address = address;
+		}
+	}
+
+	// Entity with ManyToOne type (Contact) with comnposite (ContactId) Id.
+	public class Employee
+	{
+		public virtual int Id { get; set; }
+
+		public virtual string Name { get; set; }
+
+		public virtual Contact Contact { get; set; }
+
+		public Employee()
+		{
+		}
+
+		public Employee(int id, string name)
+		{
+			Id = id;
+			Name = name;
+		}
+	}
+
+
+	public class Address
+	{
+		public virtual int Id { get; set; }
+		public virtual string PostalCode { get; set; }
+
+		public virtual string State { get; set; }
+
+		public virtual string Street { get; set; }
+
+		public Address()
+		{ }
+
+		public Address(string postalCode, string state, string street)
+		{
+			PostalCode = postalCode;
+			State = state;
+			Street = street;
+		}
+	}
+
+
+	[Serializable]
+	public class Contact
+	{
+		public virtual ContactIdentifier ContactIdentifier { get; set; }
+		public virtual string Phone { get; set; }
+	}
+
+
+	public class ContactIdentifier : IEquatable<ContactIdentifier>
+	{
+		public virtual string TypeName { get; set; }
+		public virtual string ContactId { get; set; }
+
+		public ContactIdentifier(string typeName, string contactId)
+		{
+			ContactId = contactId;
+			TypeName = typeName;
+		}
+
+		public ContactIdentifier() { }
+
+		public virtual bool Equals(ContactIdentifier other)
+		{
+			if (ReferenceEquals(null, other)) return false;
+			if (ReferenceEquals(this, other)) return true;
+			return string.Equals(TypeName, other.TypeName) && string.Equals(ContactId, other.ContactId);
+		}
+
+		public override bool Equals(object obj)
+		{
+			if (ReferenceEquals(null, obj)) return false;
+			if (ReferenceEquals(this, obj)) return true;
+			if (obj.GetType() != this.GetType()) return false;
+			return Equals((ContactIdentifier) obj);
+		}
+
+		public override int GetHashCode()
+		{
+			unchecked
+			{
+				return ((TypeName != null ? TypeName.GetHashCode() : 0) * 397) ^ (ContactId != null ? ContactId.GetHashCode() : 0);
+			}
+		}
+
+		public static bool operator ==(ContactIdentifier left, ContactIdentifier right)
+		{
+			return Equals(left, right);
+		}
+
+		public static bool operator !=(ContactIdentifier left, ContactIdentifier right)
+		{
+			return !Equals(left, right);
+		}
+
+
+
+	}
+
+
+
+}