Object with Only Id

I want to get an object from my database but only populate it with the unique id identifier. I want all other fields to be null...any ideas on how to app开发者_如何学编程roach this????

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Using NHibernate Linq provider:

Person obj = session.Query<Person>()
                    .Where(x => x.Id == id)
                    .Select(x => new Person() { Id = x.Id } )
                    .SingleOrDefault();