Question

I’m developing some things in Ruby on Rails, and I’ve currently got several models with relationships between them. Now, the models specify the relations, so I know that RoR will enforce integrity, but what about at the DB level ?

Do other people set up foreign key relationships in DB tables ? and if so, how ?, there doesn’t seem to be any way to setup/destroy a db relationship in a migration (maybe using raw SQL)

Thanks

Paul.

Answer 1

Here’s a guide on how to do it:
http://seb.box.re/2006/7/29/foreign-key-and-rails-migration

There is also a plugin for this here:
http://github.com/harukizaemon/foreign_key_migrations/tree/master

However, Rails does not easily support foreign keys in migrations for a reason. Basically they’re not really necessary when using ActiveRecord.

Here’s a good explanation of why they are not necessary and their usage is discouraged in rails: http://www.motionstandingstill.com/i-dont-use-foreign-key-constraints-with-rails/2008-10-17/

Opinions differ on this subject. There’s a good discussion here: http://forum.softiesonrails.com/forums/3/topics/138