Rails 4 - Add References Migration
I wanted to add a foreign key to an existing table using Rails’ references feature but this was not an option for existing tables. The good news is that Rails 4 makes it possible.
I prefer references
because it allows you to be lazy by automatically adding the foreign key and index.
$ rails g migration AddUserRefToProducts user:references
This migration will add a user_id
column to your products table and index it.