Fluent NHibernate automapping composite id with component - fluent-nhibernate

Question

I have this complex situation: a database of countries/regions/states/cities which primary key is composed by a code (nvarchar(3)) in a column called "Id" plus all key columns of "ancestors" (regions/states/cities).
So the table country has only one key coumn (Id) while cities has 4 key columns (Id, StateId,regionId,CountryId). Obviously they're all related, so each ancestor column is a foreign key to the related table.
I have Entities in my Model that map this relationships. But they all derive from one type called Entity<T> where T may be a simple type (string, in etc) or a complex one (a component implementing the key).
Entity<T> implements a single property called Id of type T.
For each db table, if it has a comlex key, I implement it in a separate component, which oveerides also Equals and GetHashCode() Methods (in future I'll implement those in the Entity base class).
So I have a RegionKey componet that has 2 properties (Id and CountryId).
I have conventions for Foreign Key and primary key naming and type and that is ok.
I have also Mapping ovverrides for each complex Entity.
For simplicity, lets concentrate only on Countries and Regions table. Here they are:
public class Country: Entity<string>
{
public virtual string Name { get; set; }
public virtual IList<Region> Regions { get; set; }
}
public class Region: Entity<RegionKey>
{
public virtual string Name { get; set; }
public virtual Country Country { get; set; }
}
and the RegionKey component:
namespace Hell.RealHellState.Api.Entities.Keys
{
[Serializable]
public class RegionKey
{
public virtual string Id { get; set; }
public virtual string CountryId { get; set; }
public override bool Equals(object obj)
{
if (obj == null)
return false;
var t = obj as RegionKey;
if (t == null)
return false;
return Id == t.Id && CountryId == t.CountryId;
}
public override int GetHashCode()
{
return (Id + "|" + CountryId).GetHashCode();
}
}
}
Here is the configuration of AutoPersistenceModel:
public ISessionFactory CreateSessionFactory()
{
return Fluently.Configure()
.Database(
MsSqlCeConfiguration.Standard
.ConnectionString(x=>x.Is(_connectionString))
)
.Mappings(m => m.AutoMappings.Add(AutoMappings))
.ExposeConfiguration(BuildSchema)
.BuildSessionFactory();
}
private AutoPersistenceModel AutoMappings()
{
return AutoMap.Assembly(typeof (Country).Assembly)
.IgnoreBase(typeof(Entity<>))
.Conventions.AddFromAssemblyOf<DataFacility>()
.UseOverridesFromAssembly(GetType().Assembly)
.Where(type => type.Namespace.EndsWith("Entities"));
}
private static void BuildSchema(Configuration config)
{
//Creates database structure
new SchemaExport(config).Create(false, true);
//new SchemaUpdate(config).Execute(false, true);
}
Here is the Regions entity overrides
public class RegionMappingOverride : IAutoMappingOverride<Region>
{
public void Override(AutoMapping<Region> mapping)
{
mapping.CompositeId(x=>x.Id)
.KeyProperty(x => x.Id, x=> x.ColumnName("Id").Length(3).Type(typeof(string)))
.KeyProperty(x => x.CountryId, x => x.ColumnName("CountryId").Length(3).Type(typeof(string)));
}
}
Ok now when I test this mapping I got an error saying: The data types of the columns in the relationship do not match.
I have also tried this override:
public void Override(AutoMapping<Region> mapping)
{
mapping.CompositeId()
.ComponentCompositeIdentifier(x=>x.Id)
.KeyProperty(x => x.Id.Id, x=> x.ColumnName("Id").Length(3).Type(typeof(string)))
.KeyProperty(x => x.Id.CountryId, x => x.ColumnName("CountryId").Length(3).Type(typeof(string)));
}
And it almost work but it creates a Regions table with a single column key of varbinary(8000) which is not what I want:
CREATE TABLE [hell_Regions] (
[Id] varbinary(8000) NOT NULL
, [Name] nvarchar(50) NULL
, [CountryId] nvarchar(3) NULL
);
GO
ALTER TABLE [hell_Regions] ADD CONSTRAINT [PK__hell_Regions__0000000000000153] PRIMARY KEY ([Id]);
GO
ALTER TABLE [hell_Regions] ADD CONSTRAINT [FK_Regions_Country] FOREIGN KEY ([CountryId]) REFERENCES [hell_Countries]([Id]) ON DELETE NO ACTION ON UPDATE NO ACTION;
GO
I don't have a clue of how to deal with it since it seems to me everythin is ok.
Thanks in advance for your answers

Answer 1

Ok I menaged to solve it: I had to sign the CompositeId class as MAPPED, since it is a component. So this is my new RegionMappingOverride:
public class RegionMappingOverride : IAutoMappingOverride<Region>
{
public void Override(AutoMapping<Region> mapping)
{
mapping.CompositeId(x=>x.Id)
.Mapped()
.KeyProperty(x =>x.Id,x=>x.Length(3))
.KeyProperty(x => x.CountryId, x=>x.Length(3));
}
}
Now the sql created is correct:
create table hell_Countries (
Id NVARCHAR(3) not null,
Name NVARCHAR(50) null,
primary key (Id)
)
create table hell_Regions (
Id NVARCHAR(3) not null,
CountryId NVARCHAR(3) not null,
Name NVARCHAR(50) null,
primary key (Id, CountryId)
)
alter table hell_Regions
add constraint FK_Region_Country
foreign key (CountryId)
references hell_Countries