Mapping-by-Code naming convention resembling Fluent

Recently I've posted about my first impressions about NHibernate's mapping-by-code and the one thing I was surprised was that the default naming conventions provided are not usable.

I was using default Fluent NHibernate's naming convention for quite a long time and there were only few scenarios (not counting legacy databases) when I needed to specify columns or table names on my own. With mapping-by-code it is not possible to map simple many-to-many without changing the default naming convention or specifying the names in the mapping, quite XML-style. A bit annoying.

So, as a part of my experiments with the tool, I've written another naming convention that is aimed to resemble Fluent NHibernate's default naming convention, so that:

• foreign key columns in child-parent relationships are called "Parent_id"
• many-to-many intermediate table is called "FirstToSecond" and its foreign key columns are "First_id" and "Second_id"
• on bidirectional relations, both sides match together automatically

Nothing really impressing, but missing in default mapping-by-code naming convention.

The code is here on GitHub. Feel free to use it if you find it useful. It is of course far from being complete - it's not even trying to cope with features like maps, one-to-one's, any's, many-to-any's etc.

My convention doesn't support join either and it seems that it is not possible with current mapping-by-code implementation - there's no event to attach to in case of join mapping and it looks like joins are implemented in different way. Foreign key column of joined table is called "parent_key", and can be overriden in ClassMapping only.

I'm inheriting ConventionModelMapper behaviors and adding few own rules, that are applied before mapping, so that it can be overriden in ClassMappings in a standard way. I've used few extension methods provided by NHibernate's code. It's a pity that they are not mentioned anywhere - I've just found it in the source code quite accidentally.

When using my ModelMapperWithNamingConventions in place of ModelMapper or ConventionModelMapper, many-to-many verbose mapping I've presented previously is reduced to something more friendly and quite elegant, like Fluent NHibernate has accustomed me - I can remove key column definitions from both Bag and ManyToMany mapping and remove Table name definition from Bag mapping.

public class Street
{      
    public Street()
    {
        Districts = new List<District>();
    }

    public virtual int Id { get; protected set; }
    public virtual string Name { get; set; }
    public virtual ICollection<District> Districts { get; set; }
}

public class StreetMap : ClassMapping<Street>
{
    public StreetMap()
    {
        Id(x => x.Id, m => m.Generator(Generators.Identity));
        Property(x => x.Name, m => m.Length(SqlClientDriver.MaxSizeForLengthLimitedString + 1));

        Bag(x => x.Districts, c =>
        {
            c.Key(k => k.NotNullable(true));
            c.Cascade(Cascade.All);
            c.Inverse(true);
        }, r => r.ManyToMany());
    }
}

And here are the tables generated by Hbm2dll tool: