Agile Web Development With Rails Fourth Edition by Sam Ruby
Rails just keeps on changing. Rails 3 and Ruby 1.9 bring hundreds of improvements, including new APIs and substantial performance enhancements. The fourth edition of this award-winning classic has been reorganized and refocused so it's more useful than ever before for developers new to Ruby and Rails. Rails 3 is a major release--the changes aren't just incremental, but structural. So we decided to follow suit. This book isn't just a mild reworking of the previous edition to make it run with the new Rails. Instead, it's a complete refactoring. Also, this edition reflects Ruby 1.9, a new release of Ruby with substantial functional and performance improvements.