Databases on Rails. Build a persistent domain model by mapping database tables to Ruby classes. Strong conventions for associations, validations, aggregations, migrations, and testing come baked-in.

Provides a single point of entry for using basic features of ruby ORMs

The Database Toolkit for Ruby

Squeel unlocks the power of Arel in your Rails application with a handy block-based syntax. You can write subqueries, access named functions provided by your RDBMS, and more, all without writing SQL strings. Supporting Rails 3 and 4.

Persistence and mapping toolkit for Ruby

DataMapper core library

Object Graph (Og) is a state of the art ORM system. Og serializes standard Ruby objects to Mysql, Postgres, Sqlite, KirbyBase, Filesystem and more.