A little more than a year ago, there really was only one Rails book: Agile Web Development with Rails, by Dave Thomas, David Heinemeier Hansson, and friends. Since then, about a dozen Rails books have come out. None of them, however, has replaced this seminal book as the best general resource for Rails developers.

This is not to say that there have not been some excellent books. Some do a better job at providing a gentle entry for beginners, others focus on specific areas, and many provide interesting example applications. But they are mostly tutorials, rather than references.

The Rails Way (Addison-Wesley Professional Ruby Series)

The Rails Way changes this. It is a better Rails reference than the Agile book, both because it provides more depth and because it is current with Rails 2.0. For the first time, there is a second book that is indispensable for any serious Rails developer.

The Rails Way is not a good book for someone new to Rails; there is no introductory overview, no Ruby tutorial, and no sample application. But as a reference, it is unmatched. It is very readable, despite being a reference work, because author Obie Fernandez has insights to share in almost every section. In skimming through the book, I found details in almost every section that I never quite understood before, which the books explains with sparkling clarity.

Even though it is intended primarily as a reference, The Rails Way is an outstanding tutorial for anyone who understands the basics of Rails and wants to dig deeper (and has a few days to spend reading). In this regard, it is true to its namesake book, Hal Fulton’s The Ruby Way, which holds a similar place in the Ruby world.

The Rails Way’s coverage is both deeper and broader than any other Rails book, in covering the Rails framework and associated plugins, tools, and attitudes. It weighs in at 850 pages, about 10% longer than the Agile book—and a third of the Agile book is the tutorial introduction and sample application.

If you’re working with Rails on anything but the most casual basis, you shouldn’t work without this book nearby.