PostgreSQL has partial indexes. With a partial index you tell Postgres to only index rows matching a given query.

Some uses cases for a partial index:

• You want a uniqueness index, but only under some conditions
• Your table is very large and indexing every row becomes expensive

The linked article shows how to create a partial index with Rails.

A word of caution

There should rarely be a reason for you to split up config/routes.rb. If you need to, probably your whole application should be split up.

Split it anyway

Rails::Engine looks at config.paths['config/routes.rb'] and registers its value with app.routes_reloader. This means you could put routing files anywhere and then require them. However, I recommend to put any routing files into config/routes/:

# config/routes/example.rb

Rails.application.routes.draw do
 resources :example
end

After creating y...

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

bower-rails is a great solution for managing vendored assets in your Rails app. It feels especially much more convenient and easier to update assets when going this way.

bower-rails generates a Bowerfile that works much like the Gemfile you're used to. Just specify your dependencies and run rake bower:install. You can find available packages here.

An example Bowerfile:

# ./Bowerfile
asset 'angular'
asset 'angular-i18n'
asset 'angular-ui-router'
asset 'angu...

Using beginning_of_day or end_of_day on Date or DateTime objects in Rails 2.x applications will never respect time zones, which is horrible.\
This is fixed in Rails 3, though.

Even when using Date.current or DateTime.current you will get regular Time or DateTime objects:

>> Date.current.beginning_of_day.class
=> Time # not a ActiveSupport::TimeWithZone as expected
>> DateTime.current.beginning_of_day.class
=> DateTime ...

In order to keep the controllers directory tidy, we recently started to namespace controllers. With the :controller option you can tell Rails which controller to use for a path or resource. For nested resources, Rails will determine the view path from this option, too.

That means the following code in routes.rb …

resources :users do
  resource :profile, controller: 'users/profiles' #[1]
end

… makes Rails expect the following directory structure:

app/
  controllers/
    users/
      profiles_controller.rb
    users_control...

If you need to enable NewRelic monitoring on certain machines within the same Rails environment, a simple solution is to utilize the respective hostnames of you machines.

For example, if you have 8 application servers (e.g. app1.example.com, app2.example.com, ...) and want to enable NewRelic on app1 and app2 only, utilize those steps to do so:

1. Put the attached file into your config directory (config/custom_new_relic_configuration.rb).
2. Specify on which hosts NewRelic should be enabled (see NEWRELIC_HOSTS constant and list ...

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.

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.

There are many wonderful things about Rails and the Rails ecosystem. A clean, well-lighted path for keeping all your extensions up to date is not one of them.

This is a visualization of the files that will be generated by some useful rails generators. Invoke a generator from command line via rails generate GENERATOR [args] [options]. List all generators (including rails generators) with rails g -h.

On recent/fresh installations of Ruby 1.8.7 you may encounter this error why calling any bundled binary (or just bundle exec):

/home/arne/.rvm/gems/ruby-1.8.7-p374@global/gems/rubygems-bundler-1.4.2/lib/rubygems-bundler/noexec.rb:75:in `setup': undefined method `name' for #<Array:0x7fe04783ef30> (NoMethodError)
  from /home/arne/.rvm/rubies/ruby-1.8.7-p374/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:29:in `map'
  ...

Apparently, this is due to bundler (or maybe the rubygems-bundler that RVM supplies by default) no lon...

Today, this line made me trouble. Can you spot the mistake?

match 'sitemap.xml' => 'feeds#sitemap', :constraints => { :format => 'xml' }, :as => 'sitemap'

The mistake is to match sitemap.xml. Rails will by default strip any dot-anything, remember it as desired format and forward the rest of the request to the routing engine. Since we're making .xml part of the match, it is not available for format determination and Rails will set the format to html.

Unfortunately, the constraint won't complain in this case and Rails even ren...

1. Install Ruby from the Ubuntu repository: sudo apt-get install ruby ruby-dev \
   ruby is the meta package. If you want to explicitly install 1.8 or 1.9, install ruby1.8 or ruby1.9 instead (the same applies for ruby-dev).
2. Do not install RubyGems from the repository but install the version from the webpage instead.
3. Get Bundler: sudo gem install bundler

Rails and other gems for a project should now be installed via bundle install from the...

spring ...

The most obvious way to use spring is to call it explicitly:

spring rails console
spring rake db:migrate

Binstubs

Binstubs are wrapper scripts around executables. In Rails they live inside bin/. If you run spring binstub --all, your binstubs will be using Spring.

bin/rails console
bin/rake db:migrate

bundle exec rails ...

Bundle exec is inconsistent when it comes to spring. Some commands will use it, some won't.

bundle exec rails console # starts Spring...

I got this error after upgrading Ruby from 2.4.5 to 2.6.4 when I opened the Rails console - rails server still worked.

Running via Spring preloader in process 14679
Loading development environment (Rails 5.2.2.1)
Traceback (most recent call last):
.../lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:175:in 'fork': No such file to load -- irb/encoding_aliases.rb (LoadError)
.../lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:175:in 'fork': undefined method 'reject!' for nil:NilClass (NoMethodError)
.../li...

Starting with Rails 4.0, when you get an exception reported via the ExceptionNotification gem, you will only see a very short backtrace with all backtrace lines from gems or ruby libraries missing.

This happens, because the ExceptionNotification gem uses Rails' default backtrace cleaner. To get a full backtrace in exception emails, you can remove the comment from this line in config/initializers/backtrace_silencers.rb:

Rails.backtrace_cleaner.remove_silencers!

Note that this will break the "Application Trace" functionality o...

In Rails 3.1+, instead of defining a separate up and down method you can define a single method change:

class AddComparisonFieldsToReport < ActiveRecord::Migration
  def change
    add_column :reports, :compare, :boolean
    update "UPDATE reports SET compare = #{quoted_false}"
    add_column :reports, :compare_start_date, :date
    add_column :reports, :compare_end_date, :date
  end
end

Migrating up works as expected:

b rake db:migrate
==  AddComparisonFieldsToReport: migrating ====================================
-- ad...

When you're using Sidekiq::Web to monitor the Sidekiq status AND have your session cookie configured to a wildcard domain like .example.com, you need to take an additional step to keep your cookies valid.

Issue

Sidekiq::Web is mounted into your Rails application and will use the Rails session cookie for protection from CSRF attacs. While it somehow figures out the cookie name, it does NOT respect cookie configuration like a custo...