rack-datamapper

https://github.com/mkristian/rack_datamapper

this collection of plugins helps to add datamapper functionality to Rack. there is a IdentityMaps plugin which wrappes the request and with it all database actions are using that identity map. the transaction related plugin TransactionBoundaries and RestfulTransactions wrappes the request into a transaction. for using datamapper to store session data there is the DatamapperStore.