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 [email protected]
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