Ruby on Rails guides document on Activerecord association incorrect?

Question

Wow I\'ve been struggling with this for whole day, following the \"official\" ruby on rails guides document, and just discovered that I might have been misguided by the document

Answer 1

That's right, the guide document is incorrect at the time of this writing.

The belongs_to doesn't need the :foreign_key option because AR will infer manager_id from the name of the association ("manager"). As documented, AR would raise an error when, given an Employee @dwight one attempts to @dwight.subordinates, because AR would use employee_id in the WHERE condition of the SELECT statement.

According to the AR documentation passing the :foreign_key option to has_many results in declaring the FK that will be used when generating the query for @dwight.subordinates.