Using previous_changes in an after_commit hook

previous_changes.rb

class AddFoos < ActiveRecord::Migration
  def change
    create_table :foos do |t|
      t.string :bar
    end
  end
end

class Foo < ActiveRecord::Base
  after_commit do
    puts previous_changes
  end
end

Foo.create!(bar: 'baz')
# => {"bar"=>[nil, "baz"], "id"=>[nil, 1]}