Rails - Nov 2009 - please help - complicated polymorphic association

I am trying to build a shared-appointment system, where users can
subscribe to appointments and be updated whenever changes are made to
them.  I have three objects in this system, appointments, users, and
subscribers.  Subscribers are a polymorphic object like so:
class Subscriber < ActiveRecord::Base
  belongs_to :user
  belongs_to :subscribable, :polymorphic => true
end

The tricky part is that users already own appointments, so I can''t
create a simple users.appointments association.  I can find users by
calling appointment.subscribers, but I need help getting the reverse
to work (users.subscribers.appointments)  I can use named_scope to
only grab appointment subscriber objects, but how can I make it
automatically link to the appointments, not the subscriber objects?

Hi

As subscriber model is polymorphic and as you
are referring "subscribers.appointments"
It means, you are having following association in appointment model.

class Appointment < ActiveRecord::Base
  has_many :subscribers, :as => : subscribable
end


Here goes solution

class User < ActiveRecord::Base
  has_many :subscribers

  def appointments
   self. subscribers.of_appointment_type.collect { |s| s.subscribable }
  end
end

defined "of_appointment_type" as a named_scope in Subscriber model

class Subscriber < ActiveRecord::Base
 belongs_to :user
 belongs_to :subscribable, :polymorphic => true

 named_scope :of_appointment_type, :conditions => [ "subscribable_type =
? ",
"Appointment"]

end


On Mon, Nov 2, 2009 at 1:51 AM, theLemcke
<sixtimesnine-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> I am trying to build a shared-appointment system, where users can
> subscribe to appointments and be updated whenever changes are made to
> them.  I have three objects in this system, appointments, users, and
> subscribers.  Subscribers are a polymorphic object like so:
> class Subscriber < ActiveRecord::Base
>  belongs_to :user
>  belongs_to :subscribable, :polymorphic => true
>
It means you have  subscribable_id and subscribable_type fields in table
> end
>
>
> The tricky part is that users already own appointments, so I can''t
> create a simple users.appointments association.  I can find users by
> calling appointment.subscribers, but I need help getting the reverse
> to work (users.subscribers.appointments)  I can use named_scope to
> only grab appointment subscriber objects, but how can I make it
> automatically link to the appointments, not the subscriber objects?
> >
>
Sandip
-- 
www.funonrails.com

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