Exception when using BinaryFormatter to deserialize entities with initialized proxies in associations

[dimako]

I've created a little test project which runs on .NET Framework 4.8 and using NHibernate 5.3.5 which throws:

System.ArgumentNullException: 'Value cannot be null.
   at System.Collections.Generic.HashSet`1..ctor(IEnumerable`1 collection, IEqualityComparer`1 comparer)
   at NHibernate.Proxy.NHibernateProxyFactoryInfo.CreateProxyFactory()
   at NHibernate.Proxy.NHibernateProxyObjectReference.GetRealObject(StreamingContext context)
   at System.Runtime.Serialization.ObjectManager.ResolveObjectReference(ObjectHolder holder)
   at System.Runtime.Serialization.ObjectManager.DoFixups()
   at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)
   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream)

The database design is as follows:

create table [Role]
(
    RoleID int,
    [Name] nvarchar(50),
    PRIMARY KEY (RoleID)
)

create table [Resource]
(
    ResourceID int,
    [Name] nvarchar(50),
    RoleID int,
    ManagerID int,
    PRIMARY KEY (ResourceID),
    FOREIGN KEY (RoleID) REFERENCES [Role](RoleID),
    FOREIGN KEY (ManagerID) REFERENCES [Resource](ResourceID)
)

insert [Role] (RoleID, [Name])
values (1, 'role1')
insert [Role] (RoleID, [Name])
values (2, 'role2')

insert [Resource] (ResourceID, [Name], RoleID, ManagerID)
values (1, 'res1', 1, null)

insert [Resource] (ResourceID, [Name], RoleID, ManagerID)
values (2, 'res2', 2, 1)

There are two classes:
using System;

namespace NHibernate.Bug
{
    [Serializable]
    public class Role
    {
        public virtual string Name { get; set; }
        public virtual int Key { get; set; }
    }
}

using System;

namespace NHibernate.Bug
{
    [Serializable]
    public class Resource
    {
        public virtual int Key { get; set; }
        public virtual Resource Manager { get; set; }        
        public virtual string Name { get; set; }
        public virtual Role ResourceRole { get; set; }
    }
}

and their mappings are:

<?xml version="1.0"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernate.Bug"
    namespace="NHibernate.Bug">

  <class name="Role" table="Role">
    <id name="Key">
      <column name="RoleID" sql-type="int" not-null="true"/>
      <generator class="assigned" />
    </id>
    <property name="Name"/>
  </class>

</hibernate-mapping>

<?xml version="1.0"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernate.Bug"
    namespace="NHibernate.Bug">

  <class name="Resource" table="Resource" dynamic-insert="true">
    <id name="Key" column="ResourceID" >
      <generator class="assigned" />
    </id>
    <property name="Name"/>
    <many-to-one name="Manager" class="Resource" column="ManagerID"/>
   
    <many-to-one name="ResourceRole" class="Role" column="RoleID"/>
  </class>

</hibernate-mapping>

The code that is failing is:

var session = CreateSessionFactory().OpenSession();

            // if we don't run this line the test passes
            var resource1 = session.CreateCriteria<Resource>("r").Add(Restrictions.Eq("r.Key", 2)).UniqueResult<Resource>();

            var resource2 = session.QueryOver<Resource>()
                .Where(res => res.Key == 2)
                .Fetch(SelectMode.Fetch, res => res.Manager)
                .SingleOrDefault();

            var serialised = Serialize(resource2);
            var deserialised = Deserialize(serialised);

For some reason it only fails if we execute the criteria query before the queryover one.
Please see below the full fixture code:

using Microsoft.VisualStudio.TestTools.UnitTesting;
using NHibernate.Cfg;
using NHibernate.Criterion;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

namespace NHibernate.Bug
{
    [TestClass]
    public class ProxyFixture
    {
        [TestMethod]
        public void ItShouldSerializeAndDeserialize()
        {
            var session = CreateSessionFactory().OpenSession();

            // if we don't run this line the test passes
            var resource1 = session.CreateCriteria<Resource>("r").Add(Restrictions.Eq("r.Key", 2)).UniqueResult<Resource>();

            var resource2 = session.QueryOver<Resource>()
                .Where(res => res.Key == 2)
                .Fetch(SelectMode.Fetch, res => res.Manager)
                .SingleOrDefault();

            var serialised = Serialize(resource2);
            var deserialised = Deserialize(serialised);
        }

        private ISessionFactory CreateSessionFactory()
        {
            var config = new Configuration();
            config.SetProperty(Environment.ConnectionString, "Server=xxx;Database=xxx;User Id=xxx;Password=xxx;");
            config.SetProperty(Environment.ConnectionDriver, "NHibernate.Driver.SqlClientDriver");
            config.SetProperty(Environment.Dialect, "NHibernate.Dialect.MsSql2012Dialect, NHibernate");
            config.SetProperty(Environment.ShowSql, "false");
            config.SetProperty(Environment.DefaultFlushMode, "Commit");
            config.SetProperty(Environment.FormatSql, "false");
            config.SetProperty(Environment.BatchSize, "50");
            config.AddAssembly(GetType().Assembly);              

            return config.BuildSessionFactory();
        }

        protected byte[] Serialize(object value)
        {                     
            var formatter = new BinaryFormatter();
            using (var stream = new MemoryStream())
            {
                formatter.Serialize(stream, value);
                var result = new byte[stream.Length];
                stream.Position = 0;
                stream.Read(result, 0, (int)stream.Length);
                stream.Close();
                return result;
            }
        }

        protected object Deserialize(byte[] state)
        {
            using (MemoryStream stream = new MemoryStream())
            {
                stream.Write(state, 0, state.Length);
                stream.Position = 0;
                var formatter = new BinaryFormatter();
                return formatter.Deserialize(stream);
            }
        }
    }
}

[bahusoid]

that have got lazy loaded properties

I see no lazy properties in your mappings so I changed the title to avoid confusion with properties marked as lazy="true" explicitly

[dimako]

that have got lazy loaded properties

I see no lazy properties in your mappings so I changed the title to avoid confusion.

I apologise for the confusion but if we don't specifically mark properties with lazy="false" in the mapping are they not lazy loaded?

[gliljas]

Properties are not lazy by default. Reference properties are.

[dimako]

Properties are not lazy by default. Reference properties are.

Of course! I assumed it was to do with lazy loading because I think the problem is in Role property. It is not referenced directly but I think it’s being lazy loaded during deserialization and that’s why everything is falling over. But most likely my assumption is wrong and I don’t want to mislead anyone. As you can see from the data the Resource and the Manager have different Roles. If we update them to have the same Role the issues goes away. That’s another reason I thought it had something to do with lazy loading .

[fredericDelaporte]

Isn't that #2563?

[dimako]

Isn't that #2563?

I did initially added a comment there but somebody pointed out that it looked a different issue. And the exception looks different

[dimako]

It seems the issue was caused by #1968
Hope that is helpful. Really looking forward to that being resolved!

Thank you!

[bahusoid]

Does it mean it works in 5.2?

[dimako]

Does it mean it works in 5.2?

Yes looks like it does

[fredericDelaporte]

Yes looks like it does

You mean, you think it works correctly, but have not ascertain it? For me it was not supposed to work, but maybe in a different way, like no exception on deserialization but badly initialized lazy properties.

[dimako]

Yes looks like it does

You mean, you think it works correctly, but have not ascertain it? For me it was not supposed to work, but maybe in a different way, like no exception on deserialization but badly initialized lazy properties.

It looks it was working in 5.2 but got broken after the mentioned commit was pushed in.

[bahusoid]

but badly initialized lazy properties

There is no lazy properties