Using a different foreign key with nested resources in Rails

Question

When working with nested resources in Rails is it possible to use a value/field other than the primary key of the parent resource as the foreign key for the child resource objects?

e.g. if I have "books" that belong to "authors", I pass the "author"'s primary key to the book when it's created with t.references :author, index: true in app/db/migrate/[timestamp]_create_books.rb (right?).

Is it possible to pass the author's name, instead? (Assuming that the "authors" table has a "name" field...)

I ask because I have a preexisting table of books with various fields (author, title, subject, year, etc.) and it seems simpler to create an authors table with the unique authors from the books table and then join them where authors.name=books.author instead of having to figure out a way of getting the unique primary keys from authors to associate with the correct author in books. (But I am probably totally wrong about this.) (In any case, I am curious if it can be done and/or what the proper way of bringing in the preexisting database that lacks the author-book associations would be.)

(I apologize if my terminology is off.)

Answer 1

So, your models:

class Author < ActiveRecord::Base
  has_many :books
end

class Book < ActiveRecord::Base
  belongs_to :author, primary_key: "name", foreign_key: "author_name"
end

It should work. But this way breaks one of the Rails cornerstones: "Convention over configuration" and that's why you have chances to end up with total mess in your DB someday.

And what else attributes except 'name' Author model has? If there are few of them (or even only one - 'name') it will be better and easier to have only one model 'Book' with the attribute 'author'.