Add a reference column migration in Rails 4

Question

A user has many uploads. I want to add a column to the uploads table that references the user. What should the migration look like?

Here i

Answer 1

Create a migration file

rails generate migration add_references_to_uploads user:references

Default foreign key name

This would create a user_id column in uploads table as a foreign key

class AddReferencesToUploads < ActiveRecord::Migration[5.2]
  def change
    add_reference :uploads, :user, foreign_key: true
  end
end

user model:

class User < ApplicationRecord
  has_many :uploads
end

upload model:

class Upload < ApplicationRecord
  belongs_to :user
end

Customize foreign key name:

add_reference :uploads, :author, references: :user, foreign_key: true

This would create an author_id column in the uploads tables as the foreign key.

user model:

class User < ApplicationRecord
  has_many :uploads, foreign_key: 'author_id'
end

upload model:

class Upload < ApplicationRecord
  belongs_to :user
end