Question

Quick question in RoR: Is it possible to have two fields use foreign keys from the same model?

For example, I am an employee. I want two fields: my current shop, and a shop I will be moved to in the future. In my model, how can I have two fields that are both the same foriegn key, but with different values.

It’s hard to explain…

An example

EMPLOYEE TABLE
----------------------------------------------
Name        Current Shop ID       Next Shop ID
John Doe    2                     1 

SHOP TABLE
----------------------------
ID          Shop Name
1           Jims Tools
2           Johns Tools

In the Employee model, I want both Current Shop and Next Shop to be foreign keys from the Shop model.

Answer 1

class Employee < ActiveRecord::Base
  has_one :current_shop, :class_name => Shop
  has_one :next_shop, :class_name => Shop
end

class Shop < ActiveRecord::Base
  belongs_to :current, :class_name => Employee
  belongs_to :next, :class_name => Employee
end