How to rollback Rails database migrations

When you perform database migrations in Rails you use the following command:

rake db:migrate

If you want to roll back your change to need need to find out what version your database is currently at and then roll back to a previous version:

rake db:migrate VERSION=<version to roll back to>

I've never liked this way to roll back, seems to much like hard work to me so I found a migration rollback script on the programmingishard site and simplified so that it only rollback by one version:

    namespace :db do
      namespace :migrate do
        desc "Rollback the database schema to the previous version"
        task :rollback => :environment do
          previous_version = ActiveRecord::Migrator.current_version.to_i - 1
          ActiveRecord::Migrator.migrate("db/migrate/", previous_version)
          puts "Schema rolled back to previous verison (#{previous_version})."
        end
      end

To use this scriptlet, copy and paste the code into a file called db_rollback.rake and place it the lib/tasks directory within your Rails application.

To use it to roll back your most recent migration simply run:

rake db:migrate:rollback

Technorati Tags: Ruby, Rails, Database, Migrations, Rake, Rollback, Schema, Andrew Beacock