Fluent NHibernate auto mapping - how to create a many-to-many relationship table?

Question

Hi, just wondered if anyone know if there is a way to crate a Many-to-Many relationship table automatically using some attribute? without creating the table, or mapping a class to become that relation table.

If i add the attribute [ManyToMany(3,Class="DeploymentListUsers")] i get an error that this class isn't mapped to the DB.

NHibernate.MappingException: An association from the table Users refers to an unmapped class:

I don't want to define the class myself, nor creating the table in the DB before hand.

it's seems possible in JAVA, does fluent NHibernate is a fully implemented version of hibernate and JPA annotations?

http://www.hiberbook.com/HiberBookWeb/learn.jsp?tutorial=19mappingmanytomanyrelationships

Thanks, Itay

Answer 1

If you specify a class, you must make sure it exists too. NHibernate will not create a class for you. If however, your many-to-many table only contains a foreign key to your deployments table and a foreign key to your users table, you won't need such a class. You will only need a separate many-to-many mapping class if you want to store additional facts about the relation.

As far as I can tell, in your situation you just need to create the many-to-many table (you could use NHibernate's SchemaExport() to generate the CREATE TABLE statement so there's some automation there) and tell NHibernate how to map to it. Unlike you, I don't use mapping attributes so I don't know how to do map using them but it is probably very simple.