Class that belongs_to another Class twice?

rubyonrails-talk
1

I have Class Referral which takes both a giver and receiver as a Person. As is, @person.referrals returns all referrals as appropriate. Using built in AR methods, @referral.person returns the receiver of the referral. To find out who issued the referral, I have created an instance method "giver" so that @referral.giver returns the Person who gave it. I looked at Chad Fowler's "Self-Referential MtM Models" but I'm not sure my situation is the same. The current setup I have works, but I'm not sure if there is a better Rails way to do this.

>MIGRATIONclass CreateReferrals < ActiveRecord::Migration   def self.up     create_table :referrals do |t|       t.column :giver_id, :integer, :null => false       t.column :receiver_id, :integer, :null => false       t.column :body, :text, :null => false       t.column :created_at, :datetime     end

>REFERRAL MODELclass Referral < ActiveRecord::Base   belongs_to :person

     has_one :giver, :class_name => "Person"

  validates_uniqueness_of :giver_id, :scope => :receiver_id

  def giver     Person.find(self.giver_id)   end

>PERSON MODELclass Person < ActiveRecord::Base

  has_many :referrals, :foreign_key => "receiver_id"

-- Posted viahttp://www.ruby-forum.com/.

I think you should be able to just add the has_one association to the referral model and get your attribute accessor for free...

Best,

-r

2

Ok. Here's what I've got...

## Migrations

    create_table "people" do |t|       t.column "name", :string     end     create_table "referrals" do |t|       t.column "giver_id", :integer       t.column "receiver_id", :integer     end

## Models

class Person < ActiveRecord::Base   has_many :referrals, :foreign_key => "receiver_id" end

class Referral < ActiveRecord::Base   belongs_to :receiver, :class_name => "Person", :foreign_key => "receiver_id"   belongs_to :giver, :class_name => "Person", :foreign_key => "giver_id" end

## Console

r = Person.create g = Person.create ref = Referral.create(:giver => g, :receiver => r)

r.reload g.reload

r.referrals #=> [ ref ] g.referrals #=> ref.giver #=> g ref.receiver #=> r

Best,

r