TestDOEntitySet

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace TestDOEntitySet
{
    using Xtensive.Orm;
    using Xtensive.Orm.Building;
    using Xtensive.Orm.Building.Definitions;
    using Xtensive.Orm.Configuration;

    [HierarchyRoot]
    public class MyTestEntity : Entity
    {
        [Key]
        [Field]
        public Guid Id { get; private set; }

        [Field]
        public string Name { get; set; }

        [Field]
        public EntitySet<Entity2> ES { get; set; }
    }

    [HierarchyRoot]
    public class Entity2 : Entity
    {
        [Key]
        [Field]
        public Guid Id { get; private set; }

        [Field]
        public string Name { get; set; }
    }

    internal class Program
    {
        private static void Main(string[] args)
        {
            var domainConfiguration = new DomainConfiguration("sqlserver://localhost/DO40-Tests");
            domainConfiguration.Types.Register(typeof(MyTestEntity).Assembly);
            domainConfiguration.UpgradeMode = DomainUpgradeMode.Recreate;
            using (var domain = Domain.Build(domainConfiguration))
            {
                using (var s = domain.OpenSession())
                using (s.Activate())
                using (var t = Session.Current.OpenTransaction())
                {
                    var n = 10;
                    var e1 = new MyTestEntity() { Name = "Test" };

                    var e2 = new Entity2() { Name = "1" };
                    e1.ES.Add(e2);
                    var e3 = new Entity2() { Name = "2" };
                    t.Complete();
                }

                var ds = new DisconnectedState();

                using (var s = domain.OpenSession())
                using (s.Activate())
                using (ds.Attach(s))
                using (ds.Connect())
                using (var t = Session.Current.OpenTransaction())
                {
                    var e1 = Query.All<MyTestEntity>().Single();
                    var e2 = Query.All<Entity2>().Where(a => a.Name.Contains("2")).ToArray();

                    e1.Name = "Test2"; // whithout this OK
                    
                    e1.ES.UnionWith(e2);

                    var array = e1.ES.ToArray();
                }
            }
        }
    }
}