Question

I have three models in a Ruby on Rails application:

1. Magazine
2. Product
3. Page

I want to use this query:

Magazine.find(1).products.first.pages

and get a page associated with appropriate product
but in page model I don’t want product_id be my foreign key I want number_id be my foreign key.
number is a field in product table.
how can change foreign key? because rails work with product_id as foreign key for page table.
tnx for your help.

Answer 1

I will write the appropriate codes for your models.

class Magazine < ActiveRecord::Base
  has_many :products
  has_many :pages, :through => :products
end


class Product < ActiveRecord::Base
  set_primary_key "number"
  belongs_to :magazine
  has_many :pages, foreign_key: "product_number"

  def my_pages
    self.pages.find_all { |p| p.magazine_id == self.magazine_id}
  end  
end

class Page < ActiveRecord::Base
end

You can call Magazine.first.products.first.my_pages

and it will return correct results.