from 9/16 advanced activerecord breakout

purchase.rb

class Purchase < ActiveRecord::Base
  # assumption 1: there is a class called Shirt & a table called shirts
  # assumption 2: my table has a FK called shirt_id
  belongs_to :shirt

  # assumption 1: there is a class called Purchaser & a table called purchasers 
  # assumption 2: my table has a FK called purchaser_id
  belongs_to :purchaser, class_name: :User
end

shirt.rb

class Shirt < ActiveRecord::Base
  # assumption 1: there is a table called designers & a class called Designer
  # assumption 2: i have a FK called designer_id
  belongs_to :designer, class_name: :User

  # assumption 1: there is a class called Sale & a table called sales
  # assumption 2: that table has a FK called shirt_id
  has_many :sales, class_name: :Purchase


  # assumption 1: this model has a method called sales
  # assumption 2: when I call sales, I'll get an array of objects that all have purchaser(s)
  has_many :purchasers, through: :sales
end

user.rb

class User < ActiveRecord::Base
  # assumption 1: there is a table&class called DesignedShirt
  # assumption 2: that table has a foreign key called user_id (because I am on the one side, it would be my own class name + _id)
  has_many :designed_shirts, class_name: 'Shirt', foreign_key: :designer_id

  # assumption 1: there is a table&class called Purchases
  # assumption 2: there is a FK on that table called user_id
  has_many :purchases, foreign_key: :purchaser_id


  # assumption 1: there is a method called purchases on the current model
  # assumption 2: when I call the purchases method on this model, I will get a collection of objects. those objects will have a method called purchased_shirts
  has_many :purchased_shirts, through: :purchases, source: :shirt

  # assumption 1: this model has a method called designed_shirts
  # assumption 2: when i call designed_shirts on this model, I will get a collection of objects. Each of those objects will have a method called sales
  has_many :sales, through: :designed_shirts

  # assumption 1: this model has a method called purchased_shirts
  # assumption 2: when i call purchased_shirts on this model, I will get an array of objects that all ahve the purchased_shirts method
  has_many :clients, through: :designed_shirts, source: :purchasers


  # assumption 1: the current model has a purchased_shirts method
  # assumption 2: when i call purchased_shirts on the current model, I will get a collection of objects that have the supported_designers method
  has_many :supported_designers, through: :purchased_shirts, source: :designer
end