Is it possible to use NHibernate without altering a DDD model that is part of a framework

Question

I dig a lot of things about the DDD approach (Ubiquitous language, Aggregates, Repositories, etc.) and I think that, contrary to what I read a lot, entities sho

Answer 1

Just to put my two bits in, I struggled with the same thing once but I overcame this by:

1. Adding protected default constructor to every entity.
2. Making Id virtual

Let's take for example upvote and downvote for Vote entity on my experiment website: http://chucknorrisfacts.co.uk/ (NHibernate + MySQL with Mono)

public class Vote : Entity
{
    private User _user;
    private Fact _fact;
    // true: upvote, false: downvote
    private bool _isupvoted;

    // for nHibernate
    protected Vote() { }

    public Vote(User user, Fact fact, bool is_upvoted)
    {
        Validator.NotNull(user, "user is required.");
        Validator.NotNull(fact, "fact is required.");

        _fact= fact;
        _user = user;
        _isupvoted = is_upvoted;
    }

    public User User
    {
        get { return _user; }
    }
    public Fact Fact
    {
        get { return _fact; }
    }       
    public bool Isupvoted
    {
        get { return _isupvoted; }
    }
}

This class inherits from Entity where we stick all the minimum necessary for Nhibernate.

public abstract class Entity
{
   protected int _id;
   public virtual int Id { get {return _id;} }
}

and Fluent mapping where you Reveal the private property.

public class VoteMap : ClassMap
{
    public VoteMap()
    {
       DynamicUpdate();

       Table("vote");           
       Id(x => x.Id).Column("id");

       Map(Reveal.Member("_isupvoted")).Column("vote_up_down");
       References(x => x.Fact).Column("fact_id").Not.Nullable();
       References(x => x.User).Column("user_id").Not.Nullable();
    }
}

You could probably place protected default constructor in Entity class and configure nHibernate to use it instead but I didn't look into it yet.