Nhibernate mapping - nhibernate

Question

I am trying to map Users to each other. The senario is that users can have buddies, so it links to itself
I was thinking of this
public class User
{
public virtual Guid Id { get; set; }
public virtual string FirstName { get; set; }
public virtual string LastName { get; set; }
public virtual string EmailAddress { get; set; }
public virtual string Password { get; set; }
public virtual DateTime? DateCreated { get; set; }
**public virtual IList<User> Friends { get; set; }**
public virtual bool Deleted { get; set; }
}
But am strugling to do the xml mapping.
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="MyVerse.Domain"
namespace="MyVerse.Domain" >
<class name="User" table="[User]">
<id name="Id">
<generator class="guid" />
</id>
<property name="FirstName" />
<property name="LastName" />
<property name="EmailAddress" />
<property name="Password" />
<property name="DateCreated" />
<property name="Deleted" />
<set name="Friends" table="UserFriend">
<key foreign-key="Id"></key>
<many-to-many class="User"></many-to-many>
</set>
</class>
</hibernate-mapping>

Answer 1

something like
<bag name="Friends" table="assoc_user_table" inverse="true" lazy="true" cascade="all">
<key column="friend_id" />
<many-to-many class="User,user_table" column="user_id" />
</bag>

Answer 2

Consider using the repository pattern. Create a Repository contract and a base abstract class that takes one of your entities as a type (your mapped class)
Open the session when the repository is initialized and close when destroyed. (implement IDisposable).
Then make sure all of your access to the session happens within the using statement:
[pseudo-code]:
using(var repository = RepositoryFactory<EntityType>.CreateRepository())
{
var entity = repository.get(EntityID);
foreach (somesubclass in entity.subclasscollection)
{
//Lazy loading can happen here, session is still open with the repository
... Do Something
}
}
I use a base abstract class for my Repositories. This one is for my readonly repository but you'll get the drift. They key is to keep your units of work small, open the session only when you have something to do with the database, then let it close on the dispose. Here's the base class, disclaimer YMMV:
public interface IEntity
{
int Id { get; set; }
}
public interface IRORepository<TEntity> : IDisposable where TEntity : IEntity
{
List<TEntity> GetAll();
TEntity Get(int id);
}
public abstract class RORepositoryBase<T> : IRORepository<T> where T : IEntity
{
protected ISession NHibernateSession;
protected RORepositoryBase()
{
NHibernateSession = HibernateFactory.OpenSession();
NHibernateSession.DefaultReadOnly = true;
}
public ISession Session { get { return NHibernateSession; } }
public void Dispose()
{
NHibernateSession.Flush();
NHibernateSession.Close();
NHibernateSession.Dispose();
}
public virtual List<T> GetAll()
{
return NHibernateSession.Query<T>().ToList();
}
public virtual T Get(int id)
{
return NHibernateSession.Get<T>(id);
}
}