How do I automap a component collection in Fluent NHibernate?

Question

I have a TrackLog that contains a collection of GPS points as a TrackPoint object:

public class TrackPoint
{
    public virtual int Id { get; set; }
    public virtual List<TrackPoint> TrackPoints { get;set; }
}

public class TrackLog
{
    public virtual double Latitude { get; set; }
    public virtual double Longitude { get; set; }
    public virtual DateTime Timestamp { get; set; }
}

TrackPoint is a component and I've created an IAutomappingConfiguration that tells FNH to map it as such. However, when I try to run my program, FNH spits out the following exception:

Association references unmapped class: TestProject.Components.TrackPoint

How do I map a collection of components?

Answer 1

The very first thing that needs to change is to change the List type to IList. The reason for needs is because NHibernate needs to inject its own type of collection, not C#'s own List.

What I don't understand is TrackPoint per se. You're saying that it's a component consuming itself? Could you give us more insight? I'm confused.

Say I have a class Track which consumes TrackPoint as a component:

public class TrackMap : ClassMap<TrackPoint>
{
 Id(x => x.Id);

 Component(x => x.TrackPoint, m =>
 {
      m.Map(x => x.Id);

         // Try one of the following (not sure):
         m.Map(x => x.TrackPoints);
         m.HasMany(x => x.TrackPoints);
 } 
}

Does this help?

Answer 2

I figured out my problem. Rafael, in response to your question, TrackLog has a collection of TrackPoints. Normally in this case, TrackPoint would be an entity, but because a TrackPoint should not exist if it doesn't belong in a TrackLog, I decided to make it a component, which ties its lifetime to its parent TrackLog.

It turns out the problem I was having was that, even though I created an automapping override, it wasn't working:

internal class TrackLogOverride : IAutoMappingOverride<TrackLog>
{
    public void Override(AutoMapping<TrackLog> mapping)
    {
        mapping.HasMany(x => x.TrackPoints).Component(x =>
            {
                x.Map(m => m.Latitude);
                x.Map(m => m.Longitude);
                x.Map(m => m.Timestamp);
            });
    }
}

Turns out that I needed to make the override class public for FNH to use them because I was using FNH in another assembly.