Rake task sugar for Sequel Migrations (version, migrate, rollback, reset)

gistfile1.rb

namespace :db do
  require "sequel"
  Sequel.extension :migration
  DB = Sequel.connect(ENV['DATABASE_URL'])
  
  desc "Prints current schema version"
  task :version do    
    version = if DB.tables.include?(:schema_info)
      DB[:schema_info].first[:version]
    end || 0

    puts "Schema Version: #{version}"
  end

  desc "Perform migration up to latest migration available"
  task :migrate do
    Sequel::Migrator.run(DB, "migrations")
    Rake::Task['db:version'].execute
  end
    
  desc "Perform rollback to specified target or full rollback as default"
  task :rollback, :target do |t, args|
    args.with_defaults(:target => 0)

    Sequel::Migrator.run(DB, "migrations", :target => args[:target].to_i)
    Rake::Task['db:version'].execute
  end

  desc "Perform migration reset (full rollback and migration)"
  task :reset do
    Sequel::Migrator.run(DB, "migrations", :target => 0)
    Sequel::Migrator.run(DB, "migrations")
    Rake::Task['db:version'].execute
  end    
end

possibly, you may want the same behavior as in rails, where rollback steps to previous version. In this case, use

  task :rollback, :target do |t, args|                                                                                                                                                                             
                                                                                                                                                 
    version = if DB.tables.include?(:schema_info)                                                                                                                                                                  
      DB[:schema_info].first[:version]                                                                                                                                                                             
    end || 0                                                                                                                                                                                                       
                                                                                                                                                                                                                   
    target = version.zero? ? 0 : (version - 1)                                                                                                                                                                     
    args.with_defaults(:target => target)                                                                                                                                                                          
                                                                                                                                                                                                                   
    Sequel::Migrator.run(db, "db/migrations", :target => args[:target].to_i)                                                                                                                                       
    Rake::Task['db:version'].execute                                                                                                                                                                               
  end