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

Just to document if someone has the same problem...

In my situation I've been using :uuid fields, and the above answers does not work to my case, because rails 5 are creating a column using :bigint instead :uuid:

add_reference :uploads, :user, index: true, type: :uuid

Reference: Active Record Postgresql UUID