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Whenever I create a new migration I want to make sure my down method works as well as my up. So, I always end up doing rake db:migrate, check the current version number, n, and then roll it back one using rake db:migrate VERSION=n-1. Sometimes I’m migrating up more than one version, so I want to roll back a few steps (rake db:migrate VERSION=n-3). This, of course, is cumbersome. So, I wrote a simple task to make it easier:

namespace :db do
  desc 'Rolls the schema back to the previous version. Specify the number of steps with STEP=n'
  task :rollback => :environment do
    step = ENV['STEP'] ? ENV['STEP'].to_i : 1
    version = ActiveRecord::Migrator.current_version - step
    ActiveRecord::Migrator.migrate('db/migrate/', version)
  end
end

This lets me migrate up, and roll back to the previous version easily.

$ rake db:migrate
$ rake db:rollback

And I can go back a certain number of steps just as easily.

$ rake db:rollback STEP=3

Hopefully somebody will find this as useful as I do.