foreign key referencing nonprimary key

In a legacy schema sometimes we may discover foreign key constraints
that don't follow the simple "FK references PK" rule, but "FK references
UNIQUE column" rule. Is there a way to mapping this with :foreing_key=>
... or some other mechanism with ActiveRecord?

You'll want to specify the relevant field (on both the has_many and
belongs_to) by passing the :primary_key option.

--Matt Jones

Matt Jones wrote in post #1021972: