ISession.Merge() not returning the entity id for the new entity on version 5.3.x

[Afshin1980]

I updated the NHibernate from 5.2.7 to 5.3.0 and noticed that there is a difference between the returning object from the merge function. In version 5.3.x the merge function doesn't return the entity id if the entity is not in the database but in version 5.2.7 the merge function returns the entity id. I don't know this is a bug or not

Here is the code

using NHibernate.Cfg;
using NHibernate.Dialect;
using NHibernate.Driver;
using NHibernate.Mapping.ByCode;
using NHibernate.Mapping.ByCode.Conformist;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace TestNHibernate
{
    class Program
    {
        static void Main(string[] args)
        {
            var cfg = new Configuration();

            cfg.DataBaseIntegration(x =>
            {
                x.ConnectionString = "Data Source=.;integrated security=true;Initial Catalog=TestDB;MultipleActiveResultSets=True";
                x.Driver<SqlClientDriver>();
                x.Dialect<MsSql2008Dialect>();
            });

            cfg.AddAssembly(Assembly.GetExecutingAssembly());

            var sefact = cfg.BuildSessionFactory();

            using (var session = sefact.OpenSession())
            {
                var person = new Person
                {
                    Name= "Jamie"
                };

                using (var tx = session.BeginTransaction())
                {
                    var merged = session.Merge(person);

                    session.SaveOrUpdate(merged);
                    tx.Commit();
                }
                                                
                Console.ReadLine();
            }
        }
    }

    public class Person
    {
        public virtual int ID { get; set; }
        public virtual string Name { get; set; }
        public virtual string Tel { get; set; }
    }
}

[fredericDelaporte]

This is a change coming from #1754. But it is unclear for me whether Merge should follow that change or not.

We should at least document it in the possible breaking changes of 5.3.

[bahusoid]

I'm also not sure it's intended behavior. Current behavior might be considered useful if batch entities insert is used.
For now it seems you need to wrap this call in additional session.Save if you need to save transient entity and get its ID on merge

[bahusoid]

it seems you need to wrap this call in additional session.Save

Nope. It won't save it.. Seems there is now no way to save entity on merge without actual session flush.

[fredericDelaporte]

I am going to document it as a possible breaking change of 5.3, as part of releasing 5.3.6.

@hazzik, what do think of this subject?

[hazzik]

I think Merge should behave like Save rather than Persist. So it should trigger a flush on access to the id.