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Ruby on Rails Guides (v3.1.3)

These are the new guides for Rails 3. The guides for Rails 2.3 are still available at

These guides are designed to make you immediately productive with Rails, and to help you understand how all of the pieces fit together.

Rails Guides are a result of the ongoing Guides hackfest, and a work in progress.
Guides marked with this icon are currently being worked on. While they might still be useful to you, they may contain incomplete information and even errors. You can help by reviewing them and posting your comments and corrections to the author.

Start Here

Getting Started with Rails

Everything you need to know to install Rails and create your first application.


Rails Database Migrations

This guide covers how you can use Active Record migrations to alter your database in a structured and organized manner.

Active Record Validations and Callbacks

This guide covers how you can use Active Record validations and callbacks.

Active Record Associations

This guide covers all the associations provided by Active Record.

Active Record Query Interface

This guide covers the database query interface provided by Active Record.


Layouts and Rendering in Rails

This guide covers the basic layout features of Action Controller and Action View, including rendering and redirecting, using content_for blocks, and working with partials.

Action View Form Helpers
Work in progress

Guide to using built-in Form helpers.


Action Controller Overview

This guide covers how controllers work and how they fit into the request cycle in your application. It includes sessions, filters, and cookies, data streaming, and dealing with exceptions raised by a request, among other topics.

Rails Routing from the Outside In

This guide covers the user-facing features of Rails routing. If you want to understand how to use routing in your own Rails applications, start here.

Digging Deeper

Active Support Core Extensions

This guide documents the Ruby core extensions defined in Active Support.

Rails Internationalization API

This guide covers how to add internationalization to your applications. Your application will be able to translate content to different languages, change pluralization rules, use correct date formats for each country and so on.

Action Mailer Basics
Work in progress

This guide describes how to use Action Mailer to send and receive emails.

Testing Rails Applications
Work in progress

This is a rather comprehensive guide to doing both unit and functional tests in Rails. It covers everything from "What is a test?" to the testing APIs. Enjoy.

Securing Rails Applications

This guide describes common security problems in web applications and how to avoid them with Rails.

Debugging Rails Applications

This guide describes how to debug Rails applications. It covers the different ways of achieving this and how to understand what is happening "behind the scenes" of your code.

Performance Testing Rails Applications

This guide covers the various ways of performance testing a Ruby on Rails application.

Configuring Rails Applications

This guide covers the basic configuration settings for a Rails application.

Rails Command Line Tools and Rake tasks

This guide covers the command line tools and rake tasks provided by Rails.

Caching with Rails
Work in progress

Various caching techniques provided by Rails.

Asset Pipeline

This guide documents the asset pipeline.

Extending Rails

The Basics of Creating Rails Plugins
Work in progress

This guide covers how to build a plugin to extend the functionality of Rails.

Rails on Rack

This guide covers Rails integration with Rack and interfacing with other Rack components.

Creating and Customizing Rails Generators

This guide covers the process of adding a brand new generator to your extension or providing an alternative to an element of a built-in Rails generator (such as providing alternative test stubs for the scaffold generator).

Contributing to Ruby on Rails

Contributing to Ruby on Rails

Rails is not "somebody else's framework." This guide covers a variety of ways that you can get involved in the ongoing development of Rails.

API Documentation Guidelines

This guide documents the Ruby on Rails API documentation guidelines.

Ruby on Rails Guides Guidelines

This guide documents the Ruby on Rails guides guidelines.

Release Notes

Ruby on Rails 3.1 Release Notes

Release notes for Rails 3.1.

Ruby on Rails 3.0 Release Notes

Release notes for Rails 3.0.

Ruby on Rails 2.3 Release Notes

Release notes for Rails 2.3.

Ruby on Rails 2.2 Release Notes

Release notes for Rails 2.2.


You're encouraged to help improve the quality of this guide.

If you see any typos or factual errors you are confident to patch, please clone docrails and push the change yourself. That branch of Rails has public write access. Commits are still reviewed, but that happens after you've submitted your contribution. docrails is cross-merged with master periodically.

You may also find incomplete content, or stuff that is not up to date. Please do add any missing documentation for master. Check the Ruby on Rails Guides Guidelines for style and conventions.

If for whatever reason you spot something to fix but cannot patch it yourself, please open an issue.

And last but not least, any kind of discussion regarding Ruby on Rails documentation is very welcome in the rubyonrails-docs mailing list.