NHibernate mapping by code ManyToOne with CompositeIdentity - nhibernate

Question

I am trying to convert my FluentNHibernate mappings to NHibernate Mapping By-code using NHibernate 3.3.3. The goal is to upgrade to NHibernate 3.3.3 and to cut down on the number of assemblies being distributed. I am having some trouble with translating FluentNHibernate's References mapping to a Many-To-One mapping.
Many of my entities have descriptions that need translations. For this I use a Texts table that contains these texts in all available languages. I use the text ID to reference the Texts table and then in the Data Access Object I filter the required language. This works create using NHibernate 3.1 and FluentNHibernate, with NHibernate 3.3.3 and mapping by-code however I just a MappingException saying : property mapping has wrong number of columns: Category.Description type: Text.
Where is my new mapping wrong? Or is this type of mapping not possible in NHibernate 3.3.3.
This is the Texts table (SQL-server 2008).
CREATE TABLE Texts (
ID int NOT NULL,
languageID nvarchar(10) NOT NULL,
Singular nvarchar(max) NOT NULL,
Plural nvarchar(max) NULL,
CONSTRAINT PK_Texts PRIMARY KEY CLUSTERED (ID ASC, languageID ASC)
WITH (PAD_INDEX = OFF,
STATISTICS_NORECOMPUTE = OFF,
IGNORE_DUP_KEY = OFF,
ALLOW_ROW_LOCKS = ON,
ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]
The Text class:
public class Text
{
public Text(int id, string language, string singular, string plural)
{
this.ID = new TextCompositeID(id, language);
this.Singular = singular;
this.Plural = plural;
}
public TextCompositeID ID { get; private set; }
public string Plural { get; private set; }
public string Singular { get; set; }
public override bool Equals(object obj)
{
var text = (Text)obj;
if (text == null)
{
return false;
}
return this.ID.Equals(text.ID);
}
public override int GetHashCode()
{
return this.ID.GetHashCode();
}
}
As an example here is the Category class:
public class Category
{
public int ID { get; set; }
public Text Description { get; set; }
}
The FluentNHibernate xml mapping for the Category class looks like this:
<class xmlns="urn:nhibernate-mapping-2.2"
mutable="true"
name="Category"
lazy="false"
table="Category"
where="IsObsolete=0">
<id name="ID" type="System.Int32">
<column name="ID" not-null="true" />
<generator class="native" />
</id>
<many-to-one cascade="none"
class="Text"
name="Description">
<column name="TextID"
not-null="true"
unique="false" />
</many-to-one>
</class>
Which was generated from this:
public class CategoryMap : ClassMap<Category>
{
public CategoryMap()
{
this.Table("Category");
Not.LazyLoad();
this.Where("IsObsolete=0");
Id(x => x.ID)
.Column("ID")
.GeneratedBy.Native()
.Not.Nullable();
References(x => x.Description)
.Column("DescriptionID")
.Cascade.None()
.Not.Unique()
.Not.Nullable();
}
}
This is the NHibernate ClassMapping I created:
public CategoryMap()
{
this.Lazy(false);
this.Mutable(true);
this.Table("Category");
this.Where("IsObsolete=0");
this.Id(
x => x.ID,
map =>
{
map.Column("ID");
map.Generator(Generators.Native);
});
this.ManyToOne(
x => x.Description,
map =>
{
map.Cascade(Cascade.None);
map.Class(typeof(Text));
map.Column("TextID");
map.Fetch(FetchKind.Join);
map.Lazy(LazyRelation.NoLazy);
map.ForeignKey("none");
});
}
From this I get this xml mapping:
<class name="Category"
lazy="false"
table="Category"
where="IsObsolete=0">
<id name="ID"
column="ID"
type="Int32">
<generator class="native" />
</id>
<many-to-one name="Description"
class="Text"
column="TextID"
fetch="join"
foreign-key="none"
lazy="false" />
</class>

Answer 1

I found an answer myself. I had to remove the composite ID from the Text class:
public class Text
{
public Text(int id, string language, string singular, string plural)
{
this.ID = id;
this.LanguageID = language;
this.Singular = singular;
this.Plural = plural;
}
public int ID { get; private set; }
public string LanguageID { get; private set; }
public string Plural { get; private set; }
public string Singular { get; set; }
public override bool Equals(object obj)
{
var text = (Text)obj;
if (text == null)
{
return false;
}
return this.ID.Equals(text.ID);
}
public override int GetHashCode()
{
return this.ID.GetHashCode();
}
}
The Category mapping has become:
public CategoryMap()
{
this.Lazy(false);
this.Mutable(true);
this.Table("Category");
this.Where("IsObsolete=0");
this.Id(
x => x.ID,
map =>
{
map.Column("ID");
map.Generator(Generators.Native);
});
this.ManyToOne(
x => x.Description,
map =>
{
map.Column("TextID");
map.Fetch(FetchKind.Join);
map.ForeignKey("none");
map.Lazy(LazyRelation.NoLazy);
});
}
In the Data Access Object the old QueryOver query now gets me the required result.