Nhibernate updating an entity when selecting - nhibernate

Question

I have this entity:
public class Permission
{
public virtual int Id{get;set;}
public virtual string Entity { get; set; }
public virtual bool ReadAction { get; set; }
public virtual bool UpdateAction { get; set; }
public virtual bool CreateAction { get; set; }
public virtual bool DeleteAction { get; set; }
public virtual Role Role { get; set; }
public virtual string RoleName
{
get { return Enum.GetName(typeof(Role),this.Role}
}
}
public class PermissionMap : ClassMap<Permission>
{
public PermissionMap()
{
Id(x => x.Id, "id").GeneratedBy.Identity().UnsavedValue(0);
Map(x => x.Entity);
Map(x => x.DeleteAction).CustomType<BooleanType>();
Map(x => x.ReadAction).CustomType<BooleanType>();
Map(x => x.CreateAction).CustomType<BooleanType>();
Map(x => x.UpdateAction).CustomType<BooleanType>();
Map(x => x.Role).CustomType<int>();
}
}
public enum Role
{
Administrator = 0,
SalesPerson = 1,
Marketing = 2
}
Every time I query the database it gets Updated.
I thought it is because of RoleName, but event when I have removed it its still get update.
The Permission get update for each row it has in the database.
Thanks

Answer 1

As discussed in comments, the point is, that we are all the time working with a session. It is so smart that even during read operation, it does keep track of all items by their ID.
If, any object is changed somehow (e.g. for a rendering or transfering reasons) and is still referenced by open session, it is managed as dirty one. When the session.Fulsh() is called (usually by default on transaction Commit() or even auto, depends on the FlushMode) any dirty object is persisted.
So, to avoid issuing the UPDATE statement the Entity mapping and its content must match. As at the end Shazam founded out, in this case the culprit was this mapping
// Map(x => x.Role).CustomType<int>();
Map(x => CustomType<Role>()