How to automap a collection of components with Fluent NHibernate? - nhibernate

Question

All of my entities and value objects implement marker interfaces IEntity and IValueObject. I have set them up to be treated as components like so:
public override bool IsComponent(Type type)
{
return typeof(IValueObject).IsAssignableFrom(type);
}
public override bool ShouldMap(Type type)
{
return typeof(IEntity).IsAssignableFrom(type) || typeof(IValueObject).IsAssignableFrom(type);
}
Unfortunately, this does not seem to allow entities that have collections of value objects to be automapped as component collections. For example:
public class MyEntity : IEntity
{
public IList<MyValueObject> Objects { get; set; }
}
public class MyValueObject : IValueObject
{
public string Name { get; set; }
public string Value { get; set; }
}
Is there any way to define a convention such that, any time an IEntity has an IList of a type that implements IValueObject, it gets mapped as if I had specified:
HasMany(x => x.Objects)
.Component(x => {
x.Map(m => m.Name);
x.Map(m => m.Value);
});
What I don't want to do is have to manually do these overrides for every class and write out each property for the value object again and again.

Answer 1

Create a new class that inherits from HasManyStep (FluentNHibernate.Automapping.Steps).
Override the ShouldMap() method with something like :
return base.ShouldMap(member) && IsCollectionOfComponents(member)
Add your logic to :
public void Map(ClassMappingBase classMap, Member member)
{ ... }
Replace the default step with your new one :
public class MyMappingConfiguration : DefaultAutomappingConfiguration
{
public override IEnumerable<IAutomappingStep> GetMappingSteps(AutoMapper mapper, IConventionFinder conventionFinder)
{
var steps = base.GetMappingSteps(mapper, conventionFinder);
var finalSteps = steps.Where(c => c.GetType() != typeof(FluentNHibernate.Automapping.Steps.HasManyToManyStep)).ToList();
var idx = finalSteps.IndexOf(steps.Where(c => c.GetType() == typeof(PropertyStep)).First());
finalSteps.Insert(idx + 1, new MyCustomHasManyStep(this));
return finalSteps;
}
}
Note : You could also get the original source code of HasManyStep.cs and copy it to your project to introduce your custom logic.