nhibernate insert question - have id but not entity object

Using NHibernate I need to insert an entity into a database that has a child entity. Example:

public class Reservation
{
    public int Id { get; set; }
    public Service Service { get; set; }
}

public class Service
{
    public int开发者_开发技巧 Id { get; set; }
}

I need to create a new Reservation and insert it. However, when constructing the Reservation for insertion, I don't have the Service entity, but I do have the Service's Id value. Is there a way to insert my reservation without fetching the Service first?

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You can use NHibernate's Load method. This will create a proxy for the Service object, but it will not actually hit the database. See this blog post for the difference between load and get.