Fluent NHibernate Map to private/protected Field that has no exposing Property

Question

I have the following Person and Gender classes (I don't really, but the example is simplified to get my point across), using NHibernate (Fluent NHibernate) I want to map the Database Column "GenderId" [INT] value to the protected int _genderId field in my Person class. How do I do this?

FYI, the mappings and the domain objects are in separate assemblies.

public class Person : Entity
{
    protected int _genderId;

    public virtual int Id { get; private set; }
    public virtual string Name { get; private set; }

    public virtual Gender Gender
    {
        get { return Gender.FromId(_genderId); }
    }
}

public class Gender : EnumerationBase<Gender>
{
    public static Gender Male
        = new Gender(1, "Male");

    public static Gender Female
        = new Gender(2, "Female");

    private static readonly Gender[] _genders
        = new[] { Male, Female };

    private Gender(int id, string name)
    {
        Id = id;
        Name = name;
    }

    public int Id { get; private set; }
    public string Name { get; private set; }

    public static Gender FromId(int id)
    {
        return _genders.Where(x => x.Id == id).SingleOrDefault();
    }
}

Answer 1

simply make it a protected property. NH reflection does not require public property.

protected virtual int _genderId { get; set; }

then map like so (sorry never got around to fluent)...

<property name="_genderId" column="genderId" />

also, it might be easier to just map the enum. You can have the column stored as the Enum value or text. Plenty of examples of that.

Answer 2

As dotjoe said, I think you need to expose it as a protected property. Then you could get to it using the Reveal mapping.

Your class/mapping will probably look something along the lines of

public class Person : Entity
{
    protected int genderId{ get; set; }
}


public PersonMap : ClassMap<Person>
{  
    public PersonMap()  
    {  
        Map(Reveal.Property<Person>("genderId")) 
    }  
}

There are also similar questions here and here if that helps.

Answer 3

I'm only using nHibernate for the first time, but I believe you don't need to create a protected property for this, you just have to specify access="field" in your mapping and you can map directly to the private field. E.g.

<property name="_genderId" access="field" column="GenderId"  type="Int32" />

This way there's less impact on your domain layer.