Mapping list of value objects in nhibernate

Question

I have model House which has list of doors (door represents value object)

public class House : Entity<Guid>
{
   public int Id { get; set; }
   public List<Door> Doors { get; set; }
   ...
   public House(){
      Doors = new List<Door>();
   }
}

I'm using nhibernate mapping by code approach so I tried in mapping House

HouseMap.cs

public class HouseMap: ClassMapping<House>
{
   public HouseMap()
   {
      ...
      Component(c => c.Doors, DoorMap.Mapping());
   }
}

DoorMap.cs

public class DoorMap
{
    public static Action<IComponentMapper<Door>> Mapping()
    {
        return c =>
        {
            c.Property(p => p.Number);
            c.Property(p => p.Color);             
        };
    }
}

I'm getting error on HouseMap.cs

Component(c => c.Doors, DoorMap.Mapping());

CANNOT CONVERT LAMBDA EXPRESSION TO TYPE 'STRING' BEACUSE IT IS NOT A DELEGATE TYPE

What I'm doing wrong here? Other mapping of non list value objects are fine.

Answer 1

You should for sure use interface for your C# entity:

public class House : Entity<Guid>
{
    ...
    //public List<Door> Doors { get; set; }
    public virtual IList<Door> Doors { get; set; }

And the mapping of the reference set is described here:

Mapping-by-Code - Set and Bag by Adam Bar

based on that, the Doors collection mapping should look like this (I prefer .Bag() with IList, rather than .Set() with a bit more specific ISet)

Bag(x => x.Doors, c =>
{
   ...

and these are other available settings (extract from the link above):

c.Fetch(CollectionFetchMode.Join); // or CollectionFetchMode.Select
                                   // , CollectionFetchMode.Subselect
c.BatchSize(100);
c.Lazy(CollectionLazy.Lazy); // or CollectionLazy.NoLazy, CollectionLazy.Extra

c.Table("tableName");
c.Schema("schemaName");
c.Catalog("catalogName");

c.Cascade(Cascade.All);
c.Inverse(true);

c.Where("SQL command");
c.Filter("filterName", f => f.Condition("condition"));
c.OrderBy(x => x.Name); // or SQL expression

c.Access(Accessor.Field);
c.Sort<CustomComparer>();
c.Type<CustomType>();
c.Persister<CustomPersister>();
c.OptimisticLock(true);
c.Mutable(true);
...