NHibernate - Error dehydrating property value - updating entity - nhibernate

Question

I'm having problem when saving an entity with association. Below is my code which gives the error
Fluent Class inherited from Fluent Migration
public override void Up() //Update your changes to the database
{
Create.Table("assinatura")
.WithColumn("id").AsInt32().Identity().PrimaryKey()
.WithColumn("usuario_id").AsInt32()
.WithColumn("isfreeplan").AsInt32() //1 sim 0 nao
.WithColumn("gratuito_datafinal").AsDateTime()
Create.Table("usuarios")
.WithColumn("id").AsInt32().Identity().PrimaryKey()
.WithColumn("nomecompleto").AsString(256) //Patricia dos Santos
.WithColumn("email").AsString(512) //patricia#gmail.com
.WithColumn("password").AsString(128) //123123123
Create.ForeignKey("IX_FK_AssinaturasUsuarios")
.FromTable("assinatura").ForeignColumn("usuario_id")
.ToTable("usuarios").PrimaryColumn("id");
}
Mapping of Table "Usuario"
public class UsuariosMap : ClassMapping<Usuario>
{
public enum Niveis { CADASTRADO = 0, REQUISITOU_PAGAMENTO = 1 }
public virtual int id { get; set; }
public virtual string nomecompleto { get; set; }
public virtual string email { get; set; }
public virtual string password { get; set; }
public UsuariosMap()
{
Table("usuarios");
Id(x => x.id, x => x.Generator(Generators.Identity));
Property(x => x.nomecompleto, x => x.NotNullable(true));
Property(x => x.email, x => x.NotNullable(true));
Property(x => x.password, x => x.NotNullable(true));
Bag(x => x.assinaturas, map => {
map.Table("assinatura");
map.Lazy(CollectionLazy.Lazy);
map.Inverse(true);
map.Key(k => k.Column(col => col.Name("usuario_id")));
map.Cascade(Cascade.All); //set cascade strategy
}, rel => rel.OneToMany());
}
Mapping of Table "Assinatura"
public class Assinatura
{
public virtual int Id { get; set; }
public virtual int usuario_id { get; set; }
public virtual int isfreeplan { get; set; }
public virtual DateTime gratuito_datafinal { get; set; }
public virtual Usuario usuario { get; set; }
}
public class AssinaturaMap : ClassMapping<Assinatura>
{
public AssinaturaMap()
{
Table("assinatura");
Id(x => x.Id, x => x.Generator(Generators.Identity));
Property(x => x.usuario_id, x => x.NotNullable(true));
Property(x => x.isfreeplan, x => x.NotNullable(true));
Property(x => x.gratuito_datafinal, x => x.NotNullable(true));
ManyToOne(x => x.usuario, x=>
{
x.Cascade(Cascade.DeleteOrphans);
x.Column("usuario_id");
x.ForeignKey("IX_FK_AssinaturasUsuarios");
});
}
}
When I try to update a User "Usuario" adding a new "Assinatura" I am getting an error
var user = Database.Session.Load<Usuario>(1);
var ass = new Assinatura
{
isfreeplan = 0,
gratuito_datafinal = DateTime.Now,
usuario = user
};
if (user != null)
{
user.assinaturas.Add(ass);
Database.Session.SaveOrUpdate(user);
}
An exception of type 'NHibernate.PropertyValueException' occurred in NHibernate.dll but was not handled in user code
{"Error dehydrating property value for Test.Models.Assinatura.usuario"}
Inner Exc: {"Parameter index is out of range."}
Property Name: usuario
I just want to do a basic one-to-many relationship between Usuario table and Assinature table (1 user has one or many assinaturas).

Answer 1

The exception:
Parameter index is out of range
is telling us, that we are working with one DB column twice. And that is because of this doubled mapping:
Property(x => x.usuario_id, x => x.NotNullable(true));
ManyToOne(x => x.usuario, x=>
{
x.Cascade(Cascade.DeleteOrphans);
x.Column("usuario_id");
...
It is ok to use one column for more properties (one value type, one reference).. but only for reading (loading values from DB)
For insert / update... we can use only one of these. And always is better to keep read/write reference, and property readonly
Property(x => x.usuario_id, x => {
x.NotNullable(true)
x.Insert(false)
x.Update(false)
})