DataMapper

DataMapper is a thread-safe ORM for Ruby that allows developers to easily interact with various data storage systems using a common application programming interface (a.k.a. an API).

It comes with lots of features and (official and community supported) adapters, allowing it to work with lots of mediums, keeping an uniform core, while also being able to adapt to any underlying technology.

DataMapper is quite good at detecting schemas and allowing developers to easily migrate/upgrade between them, while keeping the data's integrity intact.

There's support included for easy querying, identity maps, lazy data loading, and lots of documentation to get you started.

Features:

• Supported database drivers/adapters:
• SQLite
• PostgreSQL
• MySQL
• MongoDB
• Riak
• Redis
• MSSQL
• Windows Azure
• SimpleDB
• YAML
• RDF
• Ferret
• In-memory
• REST
• IMAP
• AppEngine
• DataStore (GAE)
• Google Data
• Google Video
• FQL
• GitHub
• ISBN DB
• JDBC
• LDAP
• AWS S3
• Salesforce
• Sphinx

What is new in this release:

• Resource[] and Resource[]= no longer fail when property name is not known
• Redundant usage of chainable was removed resulting in a better performance
• Boolean property typecasting was refactored
• Various issues with setting default Property options were fixed
• Resource#attributes= no longer use public_method_defined? - this is a security fix preventing possible DDOS attacks
• Problems with auto-migrations in multiple repositories were fixed
• Encoding problems with Binary property are fixed
• STI queries no longer include the top-level class name
• UnderscoredAndPluralizedWithoutLeadingModule naming convention was added
• belongs_to supports :unique option
• Validation of property names was improved