Rails ActiveRecord model has_one twice to the same model with different foreign keys

Question

I have model Offer with many fields, among which are there are two fields that relate to the same model:

# == Schema Information
#
# Table name: offers
#
#  id                   :integer          not null, primary key
#  name                 :string(250)      default(""), not null
#  destination_id       :integer          not null
#  cruise_line_id       :integer          not null
#  ship_id              :integer          not null
#  departure_date       :date             not null
#  departure_port_id    :integer
#  arrival_date         :date             not null
#  arrival_port_id      :integer

departure_port_id and arrival_port_id relate to the same model Port , but can be also NULL , if no departure or arrival port provided.

How should Offer and Port models look like in this case?

Answer 1

Something like this:

class Offer < ActiveRecord::Base
  belongs_to :departure_port, class_name: "Port", foreign_key: "departure_port_id"
  belongs_to :arrival_port, class_name: "Port", foreign_key: "arrival_port_id"
end

class Port < ActiveRecord::Base
  has_one :offer
end