Belongs_to primary key

I’m writing a rails application that uses a legacy database that is
imported. The legacy database has primary keys like “appno”. The new
structure in rails is going to be “id, company_id, appno” so there may
be more than one record with the same appno, but each having a unique
company_id, appno pair. id will be completely unique.

The joined record will have the structure “id, company_id, jobno, appno”
where company_id and jobno form a unique pair, and id is unique. I want
to say that the job belongs_to :applicant, :foreign_key => “appno”,
:primary_key => “appno”, :conditions => [“company_id = ?”,
self.company_id] so that it won’t use the id field on the applicant
record but will instead use the appno field. Is it possible to do this?

Jeremy W.
Serval Systems Ltd.
Tel: 01342 331940
Fax: 01342 331950