running dm migrations From http://blog.teksol.info/2008/10/16/how-to-use-datamapper-from-rails-including-migrations-and-tests

new_gist_file.rb

1 namespace :dm do
2   task :migrate => :environment do
3     gem "dm-migrations", "=0.9.6"
4     require "migration_runner"
5     Dir[File.join(Rails.root, "db", "migrate", "*")].each {|f| require f}
6     migrate_up!
7   end
8 end