change the constraint name in fluentNhibernate auto mapping alteration - oracle

Question

i'm using oracle with FluentNHibernate automapping with alterations & NHibernate
the problem is how to specify the constraint name by overriding the mapping model??
the generated sql like this:
alter table FirstTable
add constraint FK_VerLongIdentifierLongerThan30Characther
foreign key (FirstTableID)
references SecondTable;
i need to change the "FK_VerLongIdentifierLongerThan30Characther" to smaller identifier by overriding the mapping model like this:
model.Override<SomeClass>(m =>
{
m.HasOne<SomeOtherClass>(c => c.SomeProperty).?????????;
//or
m.????????
}
)

Answer 1

Instead of doing an override for each class with this problem, what I have done is create a mapping convention which would truncate objects with surpass a 30-character naming scheme on foreign keys, has many and many to many relations:
public class OracleIHasManyConvention : IHasManyConvention
{
public void Apply(IOneToManyCollectionInstance instance)
{
var keyName = string.Format(CultureInfo.InvariantCulture, "FK_{0}_{1}",
instance.Member.Name,
instance.EntityType.Name).Truncate(30);
instance.Key.ForeignKey(keyName);
}
}
public class OracleForeignKeyConvention : FluentNHibernate.Conventions.ForeignKeyConvention
{
protected override string GetKeyName(Member property, System.Type type)
{
var name = property == null
? "Id_" + type.Name.ToUnderscoredNaming()
: "Id_" + property.Name.ToUnderscoredNaming();
return name.Truncate(30);
}
}
Then I would call these conventions like this:
var cfg = Fluently.Configure()
.Database(SQLiteConfiguration.Standard.UsingFile("foobar.lite3"))
.Mappings(m => m.AutoMappings.Add(AutoMap.AssemblyOf<Product>()
.Where(a => a.Namespace == typeof (Product).Namespace)
.Conventions.Add<OracleIHasManyConvention>()
.Conventions.Add<OracleForeignKeyConvention>()
.Conventions.Add<OracleGeneralConvention>()
.Conventions.Add<CascadeAllConvention>()
));
Here's the Truncate extension:
public static class StringHelper
{
public static string Truncate(this string text, int endIndex)
{
if (text.Length > endIndex)
{
text = text.Substring(0, endIndex).TrimEnd('_');
}
return text;
}
}
I hope this is useful in any way. :)