Rails - Sep 2005 - question about associations

I have my database setup as follows (simplified for example):

table: users
id
role_id
....

table: roles
id
....

table: items
id
user_id
.....


models are:

class User < ActiveRecord::Base
  belongs_to :role
  has_many :items
  ....
end

class Role < ActiveRecord::Base
  has_many :users
  ....
end

class Item < ActiveRecord::Base
  belongs_to :user
  ....
end

from this, you can obviously see that items are ''owned'' by
users....and users belong to a particular role.  Now, my question
is...how would I enforce a relationship of some sort where items can
only owned by a user which belongs to a particular role?  Can this be
done in the model association?  or would this have to be enforced in
the business logic of the model?

something like belongs_to :users, :conditions => "role_id = 1"

Chris

Chris,

I don''t believe there is a way to specify an association condition.
You''ll need to create a custom validation method.

If you don''t envision the roles changing that much, you could also use
single table inheritance.

You could have a base User class that doesn''t have the items
associations, and then define a subclass that does have the items
association.

Cheers,

Derek

On 9/23/05, Chris Hall
<christopher.k.hall-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> I have my database setup as follows (simplified for example):
>
> table: users
> id
> role_id
> ....
>
> table: roles
> id
> ....
>
> table: items
> id
> user_id
> .....
>
>
> models are:
>
> class User < ActiveRecord::Base
>   belongs_to :role
>   has_many :items
>   ....
> end
>
> class Role < ActiveRecord::Base
>   has_many :users
>   ....
> end
>
> class Item < ActiveRecord::Base
>   belongs_to :user
>   ....
> end
>
> from this, you can obviously see that items are ''owned''
by
> users....and users belong to a particular role.  Now, my question
> is...how would I enforce a relationship of some sort where items can
> only owned by a user which belongs to a particular role?  Can this be
> done in the model association?  or would this have to be enforced in
> the business logic of the model?
>
> something like belongs_to :users, :conditions => "role_id = 1"
>
> Chris
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

--
Derek Haynes
HighGroove Studios - http://www.highgroove.com
Keeping it Simple.
404.593.4879