This repo is not supported and has a major flaw: it doesn't clean up sessions on expire. Please consider using https://github.com/minad/moneta instead:
use Rack::Session::Moneta,
store: Moneta.new(:DataMapper, setup: (ENV['DATABASE_URL'] || "sqlite://#{Dir.pwd}/development.db"))
To use with Sinatra, for example:
require 'rack-datamapper-session'
use Rack::Session::DataMapper
DataMapper.auto_upgrade!
Licensed under Do What The Fuck You Want To Public License: http://en.wikipedia.org/wiki/WTFPL