NHibernate Auditing - PostInsert Not Working - nhibernate

Question

My application has the following entities:
public class User
{
public virtual int UserID { get; set; }
public virtual string UserName { get; set; }
public virtual IList<UserLog> Log { get; private set; }
public User()
{
Log = new List<UserLog>();
}
}
public class UserLog
{
public virtual int UserLogID { get; set; }
public virtual User User { get; set; }
public virtual string UserName { get; set; }
public virtual DateTime DateCreated { get; set; }
}
With the following fluent mappings:
public class UserMap : ClassMap<User>
{
public UserMap()
{
Table("Users");
Id(x => x.UserID);
Map(x => x.UserName);
HasMany(x => x.Log)
.KeyColumn("UserID")
.OrderBy("DateCreated")
.Inverse()
.Cascade.All();
}
}
public class UserLogMap : ClassMap<UserLog>
{
public UserLogMap()
{
Table("UsersLog");
Id(x => x.UserLogID);
References(x => x.User, "UserID");
Map(x => x.UserName);
Map(x => x.DateCreated);
}
}
The UsersLog table simply logs any changes which are made to the User. I'm trying to hook this up automatically using the NHibernate event listeners. I have setup my configuration which successfully calls the following 2 methods:
public void OnPostInsert(PostInsertEvent #event)
{
if (#event.Entity is User)
InsertLog(#event.Entity);
}
public void OnPostUpdate(PostUpdateEvent #event)
{
if (#event.Entity is User)
InsertLog(#event.Entity);
}
Edit (here is the InsertLog method):
private void InsertLog(object entity)
{
var context = ServiceLocator.Current.GetInstance<IDataContext>();
var user = (User)entity;
context.Repository<UserLog>().Insert(new UserLog
{
User = user,
UserName = user.UserName,
DateCreated = DateTime.UtcNow
}); // Insert calls ISession.SaveOrUpdate(entity)
}
When i update a record a log is successfully inserted but when i insert a record i get an error telling me the UserID cannot be null in the UsersLog table. I've played around with a few different variations but nothing seems to work.
I'd really appreciate it if someone could show me how this can be done. Thanks

Answer 1

Solution posted in question comments. I simply had to use:
#event.Session.GetSession(NHibernate.EntityMode.Poco).Save(...);
to save the user instead of accessing the repository.