Question

I am working on a Ruby on Rails 3 web application and am not sure how to relate two of the models.

In our organization sales reps go out on appointments. If the appointment is successful, it will result in creating an order (which then has the items ordered related to it, but that’s for another day.) If this appointment is not successful, it will be marked as no sale and as you might have guessed, no order is created.

On the other hand, sometimes sales happen without an appointment. For example, a customer may call into the store and order something. In this case, an order can exist without an appointment.

It would be simple if there were no relationship between orders and appointments, but there has to be for ease of use for the end user. For example, if an appointment generates an order, but later the buyer cancels, they will mark the appointment as sale cancelled and then the system should automatically set the order as cancelled. Likewise,they may choose to cancel the order, then the appointment would have to be cancelled automatically by the system.

How does a developer handle something like this? Does the appointment :have_many => orders? does the order :belong_to => appointments? I don’t know what to do!

Please help me with this, I am a pretty new rails developer and I feel in over my head! Thank you!

Answer 1

As you already said, the following will work fine:

class Appointment < ActiveRecord::Base
  has_many :orders
end

class Order < ActiveRecord::Base
   belongs_to :appointment
end

belongs_to requires the field appointment_id to be present in the orders table. But, if the order is not associated with an order then appointment_id does not need to be set. You can have multiple belongs_to associations for a given class.