Rails - Apr 2005 - Simple relationship question

Hi all,

I have just started using Rails and are now trying to model a more complex
application to evaluate the framework.

I have 2 entities, Manifest and Organization. Manifest "has_many"
Organizations
and a Organzation "belongs_to" a Manifest. It works fine so far, but
the model
has a little extra: Manifest has a to-one-relationship to a single Organization
called default_organization (the Organization is yet in the organizations
collection). How I would model this? 
My first thought was a "has_one" association, but the
default_organization_id is
in the Manifest entity. I had changed it in a belongs_to, but it doesnt work too
(and is wrong in my opinion). The relationship is only a helper relationship for
smoother handling. Because the organization is already in the collection, it
must not be saved when present in the default_organization relationship. Is that
possible?

Regards,
Björn

Hi,

Your first problem is pretty easy:

class Manifest < ActiveRecord::Base
    has_many :organizations
    belongs_to :default_organization, :class_name =>
"Organization",
:foreign_key => "default_organization_id"
end

as for your second problem, the docs state:
" If you wish to assign an object to a has_one 
<http://rails.rubyonrails.com/classes/ActiveRecord/Associations/ClassMethods.html#M000396>
association without saving it, use the association.build method 
(documented below). "

Kind regards,
Flurin

Björn Weide wrote:
>Hi all,
>
>I have just started using Rails and are now trying to model a more complex
>application to evaluate the framework.
>
>I have 2 entities, Manifest and Organization. Manifest "has_many"
Organizations
>and a Organzation "belongs_to" a Manifest. It works fine so far,
but the model
>has a little extra: Manifest has a to-one-relationship to a single
Organization
>called default_organization (the Organization is yet in the organizations
>collection). How I would model this? 
>My first thought was a "has_one" association, but the
default_organization_id is
>in the Manifest entity. I had changed it in a belongs_to, but it doesnt work
too
>(and is wrong in my opinion). The relationship is only a helper relationship
for
>smoother handling. Because the organization is already in the collection, it
>must not be saved when present in the default_organization relationship. Is
that
>possible?
>
>Regards,
>Björn
>
>_______________________________________________
>Rails mailing list
>Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
>http://lists.rubyonrails.org/mailman/listinfo/rails
>  
>

Flurin Egger <f.egger.mailings@...> writes:
> 
> Hi,
> 
> Your first problem is pretty easy:
> 
> class Manifest < ActiveRecord::Base
>     has_many :organizations
>     belongs_to :default_organization, :class_name =>
"Organization",
> :foreign_key => "default_organization_id"
> end
> 
That works fine and as expected even without the build. Thanks!

Regards,
Björn