Added db:rollback to rollback the schema one version (or multiple as specified by STEP) [Jeffrey Allan Hardy]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8039 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

railties/CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Added db:rollback to rollback the schema one version (or multiple as specified by STEP) [Jeffrey Allan Hardy]
+
 * Fix typo in test_helper. Closes #9925 [viktor tron]
 
 * Request profiler.  [Jeremy Kemper]

railties/lib/tasks/databases.rake

@@ -86,6 +86,13 @@ namespace :db do
     Rake::Task["db:schema:dump"].invoke if ActiveRecord::Base.schema_format == :ruby
   end
 
+  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
+
   desc 'Drops, creates and then migrates the database for the current environment. Target specific version with VERSION=x'
   task :reset => ['db:drop', 'db:create', 'db:migrate']