Incorrect self join model example on guides.rubyonrails.org
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I feel the following self join model example given on http://guides.rubyonrails.org/association_basics.html#self-joins is incorrect.

    class Employee < ActiveRecord::Base
      has_many :subordinates, :class_name => "Employee",
        :foreign_key => "manager_id"
      belongs_to :manager, :class_name => "Employee"
    end

I feel it should be as following. Can you please suggest which one is correct and why?

    class Employee < ActiveRecord::Base
      has_many :subordinates, :class_name => "Employee",
      belongs_to :manager, :class_name => "Employee", :foreign_key => "manager_id"
    end

My rationale: The model bearing `belongs_to` relation carries the foreign_key for the model it references to. 