Rails - Apr 2005 - Models and FK enforcement?

Hey railers!

I''ve got two models that have a one-to-many relationship, should the
model
enforce the foreign key relationship?

Should the example below cause ''p.save'' to fail, as the
user_id field hasn''t
been set?  Or should I avoid creating pictures directly and create them
through a User instance?  Or should I beat it/myself with a hammer until it
doesn''t matter? ;-)

Thanks

-- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< --

CREATE TABLE `users` (
  `id` int(11) unsigned NOT NULL auto_increment,
  ..
)

CREATE TABLE `pictures` (
  `id` int(11) unsigned NOT NULL auto_increment,
  `user_id` int(11) unsigned default NULL,
 ..
)

class User < ActiveRecord::Base
  has_many :pictures
end

class Picture < ActiveRecord::Base
  belongs_to :user
end

code:
    p = Picture.new
    p.save                    # BOOM?

> I''ve got two models that have a one-to-many relationship, should
the model
> enforce the foreign key relationship?
No, the DBMS should, but you''re using MySQL with MyISAM tables, which
doesn''t enforce FK rules.
> Should the example below cause ''p.save'' to fail, as the
user_id field hasn''t
> been set?  Or should I avoid creating pictures directly and create them
> through a User instance?  Or should I beat it/myself with a hammer until it
> doesn''t matter? ;-)
It should save with a NULL foreign key, which is valid. If you specify
the FK as NOT NULL it should fail.
-- 
Phillip Hutchings
http://www.sitharus.com/
sitharus-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org /
sitharus-QrR4M9swfipWk0Htik3J/w@public.gmane.org

>> I''ve got two models that have a one-to-many relationship,
should the
model
>> enforce the foreign key relationship?
> No, the DBMS should, but you''re using MySQL with MyISAM tables,
which
> doesn''t enforce FK rules.
Ah, I was just wondering if maybe I''d missed something in my model
definition - that makes perfect sense :-)

Thanks for your quick reply,
Paul