One-To-One Orphaning Entity Issue

[aokellermann]

I am getting a strange exception thrown when committing a transaction which deletes an orphan from an unconstrained one-to-one relationship. I am using Fluent NHibernate for mappings.

There are three scenarios that I would like to work involving TenantUserPerson :

1. Save new TenantUserPerson by assigning TenantUser.TenantUserPerson.
   • No issues: Record inserts normally.
2. Delete TenantUserPerson when orphaning parent TenantUser from User.TenantUsers.
   • No issues: Record deletes normally.
3. Delete TenantUserPerson when orphaning by setting TenantUser.TenantUserPerson to null.

   • Code (in User class):

     public virtual void RemoveTenantUserPerson(Tenant tenant)
     {
         var tenantUser = TenantUsers.FirstOrDefault(x => x.Tenant.Equals(tenant));
         if (tenantUser?.TenantUserPerson != null)
         {
             tenantUser.TenantUserPerson.TenantUser = null;
             tenantUser.TenantUserPerson = null;
         }
     }

   • Generated SQL DELETE looks perfect.

   • On commit, throws:

     System.InvalidCastException: Unable to cast object of type 'TenantUserPerson' to type 'TenantUser'.
     
        at (Object )
     
        at NHibernate.Bytecode.Lightweight.AccessOptimizer.GetSpecializedPropertyValue(Object target)
     
        at NHibernate.Bytecode.AccessOptimizerExtensions.GetSpecializedPropertyValue(IAccessOptimizer optimizer, Object target)
     
        at NHibernate.Tuple.Entity.PocoEntityTuplizer.GetIdentifierPropertyValue(Object entity)
     
        at NHibernate.Tuple.Entity.AbstractEntityTuplizer.GetIdentifier(Object entity)
     
        at NHibernate.Persister.Entity.AbstractEntityPersister.GetIdentifier(Object obj)
     
        at NHibernate.Persister.Entity.AbstractEntityPersister.IsTransientAsync(Object entity, ISessionImplementor session, CancellationToken cancellationToken)
     
        at NHibernate.Engine.ForeignKeys.IsTransientFastAsync(String entityName, Object entity, ISessionImplementor session, CancellationToken cancellationToken)
     
        at NHibernate.Engine.ForeignKeys.IsTransientSlowAsync(String entityName, Object entity, ISessionImplementor session, CancellationToken cancellationToken)
     
        at NHibernate.Event.Default.DefaultDeleteEventListener.OnDeleteAsync(DeleteEvent event, ISet`1 transientEntities, CancellationToken cancellationToken)
     
        at NHibernate.Impl.SessionImpl.FireDeleteAsync(DeleteEvent event, ISet`1 transientEntities, CancellationToken cancellationToken)
     
        at NHibernate.Impl.SessionImpl.DeleteAsync(String entityName, Object child, Boolean isCascadeDeleteEnabled, ISet`1 transientEntities, CancellationToken cancellationToken)
     
        at NHibernate.Engine.Cascade.CascadePropertyAsync(Object parent, Object child, IType type, CascadeStyle style, String propertyName, Object anything, Boolean isCascadeDeleteEnabled, CancellationToken cancellationToken)
     
        at NHibernate.Engine.Cascade.CascadeOnAsync(IEntityPersister persister, Object parent, Object anything, CancellationToken cancellationToken)
     
        at NHibernate.Event.Default.AbstractFlushingEventListener.CascadeOnFlushAsync(IEventSource session, IEntityPersister persister, Object key, Object anything, CancellationToken cancellationToken)
     
        at NHibernate.Event.Default.AbstractFlushingEventListener.PrepareEntityFlushesAsync(IEventSource session, CancellationToken cancellationToken)
     
        at NHibernate.Event.Default.AbstractFlushingEventListener.FlushEverythingToExecutionsAsync(FlushEvent event, CancellationToken cancellationToken)
     
        at NHibernate.Event.Default.DefaultFlushEventListener.OnFlushAsync(FlushEvent event, CancellationToken cancellationToken)
     
        at NHibernate.Impl.SessionImpl.FlushAsync(CancellationToken cancellationToken)
     
        at NHibernate.Impl.SessionImpl.BeforeTransactionCompletionAsync(ITransaction tx, CancellationToken cancellationToken)
     
        at NHibernate.Transaction.AdoTransaction.CommitAsync(CancellationToken cancellationToken)

I have no idea why this exception is being thrown. Does anyone have any ideas?

Here are my entities and mappings:

Entities

public class User
{
	public virtual long Id { get; set; }

	public virtual ISet<TenantUser> TenantUsers { get; protected set; } = new HashSet<TenantUser>();
}

public class Tenant
{
	public virtual long Id { get; set; }
}

public class TenantUserPerson
{
	public virtual long Id { get; set; }

	public virtual TenantUser TenantUser { get; set; }
}

public class TenantUser
{
	public virtual long Id { get; set; }

	public virtual User User { get; set; }
	
	public virtual Tenant Tenant { get; set; }
	
	public virtual TenantUserPerson TenantUserPerson { get; set; }
}

Fluent Mapping

public class UserEntityMap : IAutoMappingOverride<User>
{
	public void Override(AutoMapping<User> mapping)
	{
		mapping.Id(x => x.Id)
		  .Column("UserId")
		  .GeneratedBy.Assigned();
		
		mapping.HasMany(x => x.TenantUsers)
		  .KeyColumn("UserId")
		  .LazyLoad().BatchSize(10)
		  .Cascade.AllDeleteOrphan();
	}
}

public class TenantEntityMap : IAutoMappingOverride<Tenant>
{
	public void Override(AutoMapping<Tenant> mapping)
	{
		mapping.Id(x => x.Id)
		  .Column("TenantId")
		  .GeneratedBy.Assigned();
	}
}

public class TenantUserPersonEntityMap : IAutoMappingOverride<TenantUserPerson>
{
	public void Override(AutoMapping<TenantUserPerson> mapping)
	{
	    mapping.Id(x => x.Id, "TenantUserPersonId")
	        .GeneratedBy.HiLo("5").UnsavedValue(0);
	
	    mapping.References(x => x.TenantUser).Column("TenantUserId")
		.Not.Nullable()
	        .Unique()
	        .Cascade.None();
	}
}

public class TenantUserEntityMap : IAutoMappingOverride<TenantUser>
{
	public void Override(AutoMapping<TenantUser> mapping)
	{
	    mapping.Id(x => x.Id)
	        .GeneratedBy.HiLo("5").UnsavedValue(0);
	
	    mapping.References(x => x.User).Column("UserId")
				.Cascade.None();
	    mapping.References(x => x.Tenant).Column("TenantId")
				.Cascade.None();
	
	    mapping.HasOne(x => x.TenantUserPerson)
	        .PropertyRef(x => x.TenantUser)
	        .Cascade.AllDeleteOrphan();
	}
}

See https://github.com/aokellermann/nhibernate-core/commits/feature/GH-2866