Nibernate Fluent with interface domain model and inheritance not saving - Unable to resolve property

Question

I have uploaded a gist the has a working sample, the mapping files, and the full debug log that shows the issue - https://gist.github.com/ravensorb/14193136002adbb3ec2fac07c026f921

Here is the actual exception that I am getting:

ERR: NHibernate.PropertyValueException: Error dehydrating property value for NHibernate.ConsoleTest.IOrderLine.Product ---> NHibernate.HibernateException: Unable to resolve property: Id
at NHibernate.Tuple.Entity.EntityMetamodel.GetPropertyIndex(String propertyName)
at NHibernate.Tuple.Entity.AbstractEntityTuplizer.GetPropertyValue(Object entity, String propertyPath)
at NHibernate.Persister.Entity.AbstractEntityPersister.GetPropertyValue(Object obj, String propertyName)
at NHibernate.Type.EntityType.GetReferenceValue(Object value, ISessionImplementor session)
at NHibernate.Type.ManyToOneType.NullSafeSet(DbCommand st, Object value, Int32 index, Boolean[] settable, ISessionImplementor session)
at NHibernate.Persister.Entity.AbstractEntityPersister.Dehydrate(Object id, Object[] fields, Object rowId, Boolean[] includeProperty, Boolean[][] includeColumns, Int32 table, DbCommand statement, ISessionImplementor session, Int32 index)

Here is the main part of the code that demonstrates the issue. It seems there may be an issue when working either inheritance with the Id property?

class Program
{
    static void Main(string[] args)
    {
        try
        {
            var c = new Catalog { Name = "Catalog 1" };
            var p = new Product { Name = "Sample Product", SKU = "123456789", MSRP = (decimal)1.0, Catalog = c };
            var ol = new OrderLine { Product = p, Price = p.MSRP, Qty = 1 };
            var o = new Order { CreatedOn = DateTime.Now, Lines = new List<IOrderLine> { ol } };

            if (System.IO.File.Exists("test.db"))
            {
                System.IO.File.Delete("test.db");
            }

            var sessionFactory = NHibernateUtils.CreateSessionFactory(SQLiteConfiguration.Standard.UsingFile("test.db"));

            using (var session = sessionFactory.OpenSession())
            {
                using (var transaction = session.BeginTransaction())
                {
                    session.Save(typeof(IOrder).FullName, o);

                    transaction.Commit();
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception: {0}", ex);
            if (ex.InnerException != null) Console.WriteLine("InnerException: {0}", ex.InnerException);
        }

        Console.WriteLine("Press <ENTER> to exit....");
        Console.ReadLine();
    }
}

#region Interfaces

public interface IEntity
{
    Guid Id { get; set; }
}

public interface ICataglog : IEntity
{
    string Name { get; set; }
}

public interface IProduct : IEntity
{
    string Name { get; set; }
    string SKU { get; set; }
    decimal MSRP { get; set; }
    ICataglog Catalog { get; set; }
}

public interface IOrder : IEntity
{
    DateTime CreatedOn { get; set; }
    IList<IOrderLine> Lines { get; set; }
}

public interface IOrderLine : IEntity
{
    IProduct Product { get; set; }
    int Qty { get; set; }
    decimal Price { get; set; }
}
#endregion Interfaces

#region Class Maps

public class CatalogMap : ClassMap<ICataglog>
{
    public CatalogMap()
    {
        Table("tblCatalog");

        Id(x => x.Id)
            .Column("Id")
            .GeneratedBy.Assigned();

        Map(x => x.Name);
    }
}

public class ProductMap : ClassMap<IProduct>
{
    public ProductMap()
    {
        Table("tblProduct");

        Id(x => x.Id)
            .Column("Id")
            .GeneratedBy.Assigned();

        Map(x => x.Name);
        Map(x => x.SKU);
        Map(x => x.MSRP);

        References(x => x.Catalog)
            .Cascade.SaveUpdate();
    }
}

public class OrderMap : ClassMap<IOrder>
{
    public OrderMap()
    {
        Table("tblOrder");

        Id(x => x.Id)
            .Column("Id")
            .GeneratedBy.Assigned();

        Map(x => x.CreatedOn);

        HasMany(x => x.Lines)
            .Cascade.All()
            .KeyColumns.Add("Id");
    }
}

public class OrderLineMap : ClassMap<IOrderLine>
{
    public OrderLineMap()
    {
        Table("tbOrderLine");

        Id(x => x.Id)
            .Column("Id")
            .GeneratedBy.Assigned();

        Map(x => x.Qty);
        Map(x => x.Price);

        References(x => x.Product)
            .Cascade.SaveUpdate()
            .PropertyRef(x => x.Id)
            .ForeignKey("productId");
    }
}
#endregion Class Maps

public static class NHibernateUtils
{
    public static ISessionFactory CreateSessionFactory(IPersistenceConfigurer persistenceConfigurer)
    {
        return Fluently.Configure()
            .Database(persistenceConfigurer)
            .Mappings(m =>
            {
                m.FluentMappings.Add<CatalogMap>();
                m.FluentMappings.Add<ProductMap>();
                m.FluentMappings.Add<OrderMap>();
                m.FluentMappings.Add<OrderLineMap>();

                m.FluentMappings.ExportTo(System.Environment.CurrentDirectory);
            })
            .ExposeConfiguration(c => new SchemaExport(c).Create(false, true))
            .BuildConfiguration()
            .BuildSessionFactory();
    }
}

if you want to see the mapping files that are generated or want to repro the issue - check out the gist

Answer 1

I think you use the wrong id generator. Check this and Fluent NHibernate Generated AND Assigned ID Columns.

Assigned means that NHibernate will try to insert the entity with already initialized identifier(not generate it by itself) - kind of SET IDENTITY_INSERT [dbo].[TableName] ON.

Try to use this:

Id(x => x.Id).GeneratedBy.Guid();

//Id(x => x.Id).GeneratedBy.Increment();//for numbers
//Id(x => x.Id).GeneratedBy.Identity();//for numbers

Update:

If you want to use Id(x => x.Id).GeneratedBy.Assigned() then make sure you explicitly assigned identifiers for all entities:

 var c = new Catalog { Name = "Catalog 1", Id = Guid.NewGuid() };
 var p = new Product { Name = "Sample Product", SKU = "123456789", MSRP = (decimal)1.0, Catalog = c, Id = Guid.NewGuid() };
 var ol = new OrderLine { Product = p, Price = p.MSRP, Qty = 1, Id = Guid.NewGuid() };
 var o = new Order { CreatedOn = DateTime.Now, Lines = new List<IOrderLine> { ol }, Id = Guid.NewGuid() };

 session.Save(typeof(ICatalog).FullName, c);
 session.Save(typeof(IProduct).FullName, p);
 session.Save(typeof(IOrderLine).FullName, ol);
 session.Save(typeof(IOrder).FullName, o);

 transaction.Commit();

Update 2:

I found that .KeyColumns.Add("Id") and .PropertyRef(x => x.Id).ForeignKey("productId") are causing your exception(not sure whats wrong with this). Try to comment those lines and you will not have an error.