How do I create a foreign key in rails 5 if I've already created the models for the tables I want to associate?

Question

All of the references I've found either show me how to do it upon table creation, or are for a much earlier version of rails. Ideally, I'd like like the foreign_key to be named 'author_id' in the questions table to distinguish it from other users who may be leaving comments or answers later.

class Question < ApplicationRecord
  belongs_to :user
end

class User < ApplicationRecord
  has_many :questions
end

Answer 1

You can create a new empty migration file in your terminal via rails generate migration RenameUserFkOnQuestion. Open it up and build your migration. This is a handy guide if you're not sure on the name of something.

def change
  change_table :questions do |t|
    t.rename :user_id, :author_id
  end
end

Run the migration and head over to your models. You'll need to update your relationships like so:

class Question
  belongs_to :author, class_name: 'User'
end

class User
  has_many :questions, inverse_of: :author
end

Then you should be good to go.