NHibernate multi column ManyToOne mapping with Mapping By-Code - 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.
However when I compile and run I get the following exception:
NHibernate.MappingException: Multi-columns property can't be mapped through single-column API.
The XML mapping FluentNHibernate gets my looks like this:
<many-to-one cascade="none" class="TextDto" fetch="join" lazy="false" name="Name" not-found="ignore">
<column name="NameTextId" unique="false" />
<column name="LanguageId" unique="false" />
</many-to-one>
Here is my new By-Code mapping:
this.ManyToOne(u => u.Name, c =>
{
c.Cascade(Cascade.None);
c.Class(typeof(TextDto));
c.Columns(
x =>
{
x.Name("NameTextId");
x.Unique(false);
},
x =>
{
x.Name("LanguageId");
x.Unique(false);
});
c.Fetch(FetchKind.Join);
c.Lazy(LazyRelation.NoLazy);
c.NotFound(NotFoundMode.Ignore);
c.Unique(false);
});
This is the old FluentNHibernate mapping:
References(x => x.Name)
.Columns("NameTextId", "LanguageId")
.Cascade.None()
.Fetch.Join()
.NotFound.Ignore()
.Not.Unique()
.Not.LazyLoad();
For Completeness the property type involved:
public class TextDto
{
public TextCompositeId Id { get; set; }
public string PluralText { get; set; }
public string SingularText { get; set; }
public override bool Equals(object obj)
{
var text = (TextDto)obj;
if (text == null) return false;
return this.Id.Equals(text.Id);
}
public override int GetHashCode()
{
return this.Id.GetHashCode();
}
}
And an example of the property in an entity:
public class CharacteristicValue
{
public CharacteristicValueCompositeId Id { get; set; }
public TextDto Name { get; set; }
public string LanguageIdentity { get; set; }
public string Value
{
get
{
string value = null;
if (this.ValueMultilingual != null) return this.ValueMultilingual.SingularText;
else if (!string.IsNullOrEmpty(this.ValueMeta)) return this.ValueMeta;
return value;
}
}
public TextDto ValueMultilingual { get; set; }
public string ValueMeta { get; set; }
public override bool Equals(object obj)
{
if (obj == null) return false;
if (object.ReferenceEquals(this, obj)) return true;
CharacteristicValue characteristicValue = obj as CharacteristicValue;
if (characteristicValue == null) return false;
if (this.Id != characteristicValue.Id) return false;
return true;
}
public override int GetHashCode()
{
return this.Id.GetHashCode();
}
}
So, how do I get the xml-mapping I used to get with FluentNHibernate but with NHiberbate's Mapping By-Code?

Answer 1

In your mapping, remove the c.Unique(false); from the ManyToOne mapping. This setting we do apply for each column now.
this.ManyToOne(u => u.Name, c =>
{
... // the same as above
// c.Unique(false); // it is setting now related to columns
});
And you will recieve
<many-to-one name="Name" class="TextDto" fetch="join" lazy="false" not-found="ignore">
<column name="NameTextId" unique="true" />
<column name="LanguageId" />
</many-to-one>
If you will change uniqueness on one of the columns:
x =>
{
x.Name("NameTextId");
x.Unique(true); // change here
},
The unique constraint would be added to that column:
<column name="NameTextId" unique="true" />