Ever wondered if there is a reverse for Rails' .each(&:to_s) idiom? Turns out there is...

You probably already know, that you can abbreviate code like

dogs.each { |dog| dog.bark! }

with

dogs.each(&:bark!)

Now suppose it is the other way round and you have

bones.each { |bone| dog.eat!(bone) }

Good old Ruby already has a solution:

bones.each(&dog.method(:eat!))

There is a bug in Rails 3's dbconsole script, which makes the following command open a database console for the development environment:

rails dbconsole -p test

You need to write this instead:

rails dbconsole test -p

Passenger gives you the possibility to define in which environment your app should be started.
This has to be added to the VirtualHost configuration for Apache for Rails 2 applications:

RailsEnv development

When running Rails 3, you need

RackEnv development

Adds missing native PostgreSQL data types to ActiveRecord and convenient querying extensions for ActiveRecord and Arel for Rails 4.x

Common table expressions

• Relation#with
• Model.from_cte

Arrays

Face.where.contains tags: %w[happy smiling] # Matching faces have both 'happy' and 'smiling' tags
Face.where.overlap tags: %w[happy smiling] # Matching faces have at least one of these tags
Face.where.any tags: 'happy' # Matching faces include the 'happy' tag
Face.where.all tags: 'dunno' # Not documented, try for yourself

...

Free Hoptoad/Airbrake alternative which can capture exceptions from any platform. It comes with a Rails notifier and a RESTful API to write your own notifiers for Javascript, etc.

Should we some day wish to do away with the current way we deal with exceptions, this might be a good place to start.

Our new scope-based authorization gem for Ruby on Rails has been released. This might one day replace Aegis as our standard authorization solution.

Adds a slide out panel to your Rails application that directs clients to test stories that have been marked as 'delivered' in Pivotal Tracker.

Wrapper from Globalite API to the Rails 2.2 I18n API

I am a huge fan of SASS (Syntactically Awesome Stylesheets) for styling Rails applications. I have been using it on all of my projects for quite a while now and have developed some great techniques that make it much easier to organize, write, and read stylesheets in an application

Noel Rappin discusses ways to keep up with edge Rails.

A Rails FormBuilder with semantically rich and accessible markup.

Rails’ script/console makes it easy to fetch, view and edit your database records. But can you edit those records as quickly as you edit code in your text editor? Riiight, like editing our database records in an editor is gonna happen? It already has.

Simplifies plugin testing by creating an isolated Rails environment that simulates its usage in a real application

A Rails plugin that delivers a special message to DiggBar users, or runs frame-killer javascript.

Effortless backend interface for Ruby on Rails applications. (Admin scaffold generator.)

Metric_fu is a set of rake tasks that make it easy to generate metrics reports. It uses Saikuro, Flog, Flay, Rcov, Reek, Roodi, Subversion, Git, and Rails built-in stats task to create a series of reports. It's designed to integrate easily with CruiseControl.rb by placing files in the Custom Build Artifacts folder.

Rails extensions to simplify internationalization

Read_from_slave for Rails enables database reads from a slave database, while writes continue to go to the master

A/Bingo is a Ruby on Rails A/B testing framework written as a plugin.

Stop writing your own random string generators. Rails does this for you.

A rails plugin to store a collection of boolean attributes in a single ActiveRecord column as a bit field.

Ambitious Query Indexer is a Rails plugin to identify database indexes that are missing. Rather than looking at tables and guessing what needs indexing, it will locate and run as many queries as it can find and suggest indexes that could be added based upon its findings.

Rails plugin which adds a convenient way to override attr_accessible protection.... You can mark certain attributes as trusted for different roles.

Asset Fingerprint Plugin for Ruby on Rails - allows you to use md5 or timestamps in query string or in asset filenames as suggested by Google Page Speed