Rails can swap a varchar column for an ENUM without changing application code, reducing risk when tightening database constraints.

Rails 3 lets applications define custom configuration elements directly, avoiding extra gems or plugins for miscellaneous settings.

Rails 3.1 asset pipeline issues in production can break precompiling, fingerprinting, and stylesheet rendering when Haml, Sass, and Compass are involved.

Rails 3.0 has been underway for a good two years, so it’s with immense pleasure that we can declare it’s finally here. We’ve brought the work of more than 1,600 contributors together to make everything better, faster, cleaner, and more beautiful.

Learn everything you need to know about Scaling your Rails app through 13 informative Screencasts produced by Gregg Pollack with the support of New Relic.

There are a bunch of basic functional elements to building out a popular Rails app that I've never really seen explained in one place, but we had to learn the hard way while building Posterous.

A thorough introduction to web development with Ruby on Rails

Rails 3 auto-converts ActiveRecord times to UTC by default, which can break code using Time.now or Time.parse; local time and non-aware attributes restore the older behavior.

Rails 5 migration classes are versioned with ActiveRecord::Migration[5.0] so the migration API can evolve without breaking historical files in db/migrate.

jsonb in PostgreSQL 9.4 stores JSON differently from json and suits queries, indexing, and Rails 4.2 integration better for many use cases.

Rails localisation can be managed with remotely editable translations, simplifying updates for multilingual applications without redeploying code.

Absolute URLs in Rails tests can be treated as external because the host is unknown, breaking redirect handling in Webrat. Use path-only matching or reset Webrat to the local site.

Public file links in email can lose host and port information; combining root_url with a CarrierWave file path keeps contract URLs usable in mailers.

A join model can enforce a single associated record when a foreign key on the target model is not possible; validates_uniqueness_of on the join row limits the relation to one.

Rails 5 upgrade can fail when the database schema lacks configured environment data, especially during parallel test database migration.

Katapult reduced the effort of bootstrapping Rails apps, but its maintenance cost outweighed the gains and development has ended.

Database constraints for comments and users help enforce referential integrity, but support is limited to certain adapters and can surface ActiveRecord::InvalidForeignKey errors.

Capybara's save_and_open_page files can clutter the Rails root when debugging Cucumber scenarios. Set Capybara.save_and_open_page_path to store them elsewhere.

When CoffeeScript was added to Rails 3.1 they forgot one very important part, the ability to use it when responding to JavaScript (JS) requests!

In Rails 3.1 it’s incredibly easy to build your application’s JavaScript using CoffeeScript, however if you fire off an AJAX request to your application you can only write your response using regular JavaScript and not CoffeeScript, at least until CoffeeBeans came along.

Browsers may keep PATCH and DELETE on 302 redirects instead of switching to GET, breaking AJAX flows. Use 303 See Other or POST method override to force a GET follow-up.

PostgreSQL partial indexes reduce index size and write overhead by indexing only rows that match a condition, useful for conditional uniqueness and large tables.

Rails specs can get controller, model, or request helpers from directory-based inference; :type forces the desired context even when a file lives elsewhere.

I have been playing around with RESTful Rails recently. Below is my collection or Rails REST howtos, tutorials and other resources I have found so far.

ObjectiveResource is an Objective-C port of Ruby on Rails' ActiveResource. It provides a way to serialize objects to and from Rails' standard RESTful web-services (via XML or JSON) and handles much of the complexity involved with invoking web-services of any language from the iPhone.