Rails 2.2 delivers a number of new and improved features. This list covers the major upgrades, but doesn't include every little bug fix and change. If you want to see everything, check out the list of commits in the main Rails repository on GitHub.
Along with Rails, 2.2 marks the launch of the Ruby on Rails Guides, the first results of the ongoing Rails Guides hackfest. This site will deliver high-quality documentation of the major features of Rails.
Rails 2.2 is a significant release for the infrastructure that keeps Rails humming along and connected to the rest of the world.
Rails 2.2 supplies an easy system for internationalization (or i18n, for those of you tired of typing).
Lead Contributors: Rails i18 Team
More information :
Along with thread safety, a lot of work has been done to make Rails work well with JRuby and the upcoming Ruby 1.9. With Ruby 1.9 being a moving target, running edge Rails on edge Ruby is still a hit-or-miss proposition, but Rails is ready to make the transition to Ruby 1.9 when the latter is released.
The internal documentation of Rails, in the form of code comments, has been improved in numerous places. In addition, the Ruby on Rails Guides project is the definitive source for information on major Rails components. In its first official release, the Guides page includes:
All told, the Guides provide tens of thousands of words of guidance for beginning and intermediate Rails developers.
If you want to generate these guides locally, inside your application:
rake doc:guides
This will put the guides inside Rails.root/doc/guides
and you
may start surfing straight away by opening
Rails.root/doc/guides/index.html
in your favourite browser.
Lead Contributors: Rails Documentation Team
Major contributions from Xavier Noria“:http://advogato.org/person/fxn/diary.html and ”Hongli Lai
More information:
Supporting the etag and last modified timestamp in HTTP headers means that Rails can now send back an empty response if it gets a request for a resource that hasn't been modified lately. This allows you to check whether a response needs to be sent at all.
class ArticlesController < ApplicationController def show_with_respond_to_block @article = Article.find(params[:id]) # If the request sends headers that differs from the options provided to stale?, then # the request is indeed stale and the respond_to block is triggered (and the options # to the stale? call is set on the response). # # If the request headers match, then the request is fresh and the respond_to block is # not triggered. Instead the default render will occur, which will check the last-modified # and etag headers and conclude that it only needs to send a "304 Not Modified" instead # of rendering the template. if stale?(:last_modified => @article.published_at.utc, :etag => @article) respond_to do |wants| # normal response processing end end end def show_with_implied_render @article = Article.find(params[:id]) # Sets the response headers and checks them against the request, if the request is stale # (i.e. no match of either etag or last-modified), then the default render of the template happens. # If the request is fresh, then the default render will return a "304 Not Modified" # instead of rendering the template. fresh_when(:last_modified => @article.published_at.utc, :etag => @article) end end
The work done to make Rails thread-safe is rolling out in Rails 2.2. Depending on your web server infrastructure, this means you can handle more requests with fewer copies of Rails in memory, leading to better server performance and higher utilization of multiple cores.
To enable multithreaded dispatching in production mode of your application,
add the following line in your
config/environments/production.rb
:
config.threadsafe!
More information :
There are two big additions to talk about here: transactional migrations and pooled database transactions. There's also a new (and cleaner) syntax for join table conditions, as well as a number of smaller improvements.
Historically, multiple-step Rails migrations have been a source of trouble.
If something went wrong during a migration, everything before the error
changed the database and everything after the error wasn't applied.
Also, the migration version was stored as having been executed, which means
that it couldn't be simply rerun by rake db:migrate:redo
after you fix the problem. Transactional migrations change this by wrapping
migration steps in a DDL transaction, so that if any of them fail, the
entire migration is undone. In Rails 2.2, transactional migrations are
supported on PostgreSQL out of the box. The code is extensible to other
database types in the future - and IBM has already extended it to support
the DB2 adapter.
Lead Contributor: Adam Wiggins
More information:
Connection pooling lets Rails distribute database requests across a pool of
database connections that will grow to a maximum size (by default 5, but
you can add a pool
key to your database.yml
to
adjust this). This helps remove bottlenecks in applications that support
many concurrent users. There's also a wait_timeout
that
defaults to 5 seconds before giving up.
ActiveRecord::Base.connection_pool
gives you direct access to
the pool if you need it.
development: adapter: mysql username: root database: sample_development pool: 10 wait_timeout: 10
Lead Contributor: Nick Sieger
More information:
You can now specify conditions on join tables using a hash. This is a big help if you need to query across complex joins.
class Photo < ActiveRecord::Base belongs_to :product end class Product < ActiveRecord::Base has_many :photos end # Get all products with copyright-free photos: Product.all(:joins => :photos, :conditions => { :photos => { :copyright => false }})
More information:
Two new sets of methods have been added to Active Record's dynamic finders family.
find_last_by_attribute
¶ ↑The find_last_by_attribute
method is equivalent to
Model.last(:conditions => {:attribute => value})
# Get the last user who signed up from London User.find_last_by_city('London')
Lead Contributor: Emilio Tagua
find_by_attribute!
¶ ↑The new bang! version of find_by_attribute!
is equivalent to
Model.first(:conditions => {:attribute => value}) || raise
ActiveRecord::RecordNotFound
Instead of returning nil
if it can't find a matching record, this method will raise an exception
if it cannot find a match.
# Raise ActiveRecord::RecordNotFound exception if 'Moby' hasn't signed up yet! User.find_by_name!('Moby')
Lead Contributor: Josh Susser
Active Record association proxies now respect the scope of methods on the
proxied object. Previously (given User has_one :account)
@user.account.private_method
would call the private method on
the associated Account object. That fails in Rails 2.2; if you need this
functionality, you should use
@user.account.send(:private_method)
(or make the method public
instead of private or protected). Please note that if you're overriding
method_missing
, you should also override
respond_to
to match the behavior in order for associations to
function normally.
Lead Contributor: Adam Milligan
More information:
rake db:migrate:redo
now accepts an optional VERSION to target
that specific migration to redo
Set config.active_record.timestamped_migrations = false
to
have migrations with numeric prefix instead of UTC timestamp.
Counter cache columns (for associations declared with :counter_cache
=> true
) do not need to be initialized to zero any longer.
ActiveRecord::Base.human_name
for an
internationalization-aware humane translation of model names
On the controller side, there are several changes that will help tidy up your routes. There are also some internal changes in the routing engine to lower memory usage on complex applications.
Shallow route nesting provides a solution to the well-known difficulty of using deeply-nested resources. With shallow nesting, you need only supply enough information to uniquely identify the resource that you want to work with.
map.resources :publishers, :shallow => true do |publisher| publisher.resources :magazines do |magazine| magazine.resources :photos end end
This will enable recognition of (among others) these routes:
/publishers/1 ==> publisher_path(1) /publishers/1/magazines ==> publisher_magazines_path(1) /magazines/2 ==> magazine_path(2) /magazines/2/photos ==> magazines_photos_path(2) /photos/3 ==> photo_path(3)
Lead Contributor: S. Brent Faulkner
More information:
You can now supply an array of methods for new member or collection routes. This removes the annoyance of having to define a route as accepting any verb as soon as you need it to handle more than one. With Rails 2.2, this is a legitimate route declaration:
map.resources :photos, :collection => { :search => [:get, :post] }
Lead Contributor: Brennan Dunn
By default, when you use map.resources
to create a route,
Rails generates routes for seven default actions (index, show, create, new,
edit, update, and destroy). But each of these routes takes up memory in
your application, and causes Rails to generate additional routing logic.
Now you can use the :only
and :except
options to
fine-tune the routes that Rails will generate for resources. You can supply
a single action, an array of actions, or the special :all
or
:none
options. These options are inherited by nested
resources.
map.resources :photos, :only => [:index, :show] map.resources :products, :except => :destroy
Lead Contributor: Tom Stuart
You can now easily show a custom error page for exceptions raised while routing a request.
The HTTP Accept header is disabled by default now. You should prefer the
use of formatted URLs (such as /customers/1.xml
) to indicate
the format that you want. If you need the Accept headers, you can turn them
back on with config.action_controller.use_accept_header =
true
.
Benchmarking numbers are now reported in milliseconds rather than tiny fractions of seconds
Rails now supports HTTP-only cookies (and uses them for sessions), which help mitigate some cross-site scripting risks in newer browsers.
redirect_to
now fully supports URI schemes (so, for example,
you can redirect to a svn`ssh: URI).
render
now supports a :js
option to render plain
vanilla JavaScript with the right mime type.
Request forgery protection has been tightened up to apply to HTML-formatted content requests only.
Polymorphic URLs behave more sensibly if a passed parameter is nil. For
example, calling polymorphic_path([@project, @date, @area])
with a nil date will give you project_area_path
.
javascript_include_tag
and stylesheet_link_tag
support a new :recursive
option to be used along with
:all
, so that you can load an entire tree of files with a
single line of code.
The included Prototype JavaScript library has been upgraded to version 1.6.0.3.
RJS#page.reload
to reload the browser's current location
via JavaScript
The atom_feed
helper now takes an :instruct
option to let you insert XML processing instructions.
Action Mailer now supports mailer layouts. You can make your HTML emails as
pretty as your in-browser views by supplying an appropriately-named layout
- for example, the CustomerMailer
class expects to use
layouts/customer_mailer.html.erb
.
More information:
Action Mailer now offers built-in support for GMail's SMTP servers, by turning on STARTTLS automatically. This requires Ruby 1.8.7 to be installed.
Active Support now offers built-in memoization for Rails applications, the
each_with_object
method, prefix support on delegates, and
various other new utility methods.
Memoization is a pattern of initializing a method once and then stashing its value away for repeat use. You've probably used this pattern in your own applications:
def full_name @full_name ||= "#{first_name} #{last_name}" end
Memoization lets you handle this task in a declarative fashion:
extend ActiveSupport::Memoizable def full_name "#{first_name} #{last_name}" end memoize :full_name
Other features of memoization include unmemoize
,
unmemoize_all
, and memoize_all
to turn
memoization on or off.
Lead Contributor: Josh Peek
More information:
The each_with_object
method provides an alternative to
inject
, using a method backported from Ruby 1.9. It iterates
over a collection, passing the current element and the memo into the block.
%w(foo bar).each_with_object({}) { |str, hsh| hsh[str] = str.upcase } #=> {'foo' => 'FOO', 'bar' => 'BAR'}
Lead Contributor: Adam Keys
If you delegate behavior from one class to another, you can now specify a prefix that will be used to identify the delegated methods. For example:
class Vendor < ActiveRecord::Base has_one :account delegate :email, :password, :to => :account, :prefix => true end
This will produce delegated methods vendor#account_email
and
vendor#account_password
. You can also specify a custom prefix:
class Vendor < ActiveRecord::Base has_one :account delegate :email, :password, :to => :account, :prefix => :owner end
This will produce delegated methods vendor#owner_email
and
vendor#owner_password
.
Lead Contributor: Daniel Schierbeck
Extensive updates to ActiveSupport::Multibyte
, including Ruby
1.9 compatibility fixes.
The addition of ActiveSupport::Rescuable
allows any class to
mix in the rescue_from
syntax.
past?
, today?
and future?
for
Date
and Time
classes to facilitate date/time
comparisons.
Array#second
through Array#fifth
as aliases for
Array#[1]
through Array#[4]
Enumerable#many?
to encapsulate collection.size >
1
Inflector#parameterize
produces a URL-ready version of its
input, for use in to_param
.
Time#advance
recognizes fractional days and weeks, so you can
do 1.7.weeks.ago
, 1.5.hours.since
, and so on.
The included TzInfo library has been upgraded to version 0.3.12.
ActiveSuport::StringInquirer
gives you a pretty way to test
for equality in strings:
ActiveSupport::StringInquirer.new("abc").abc? =>
true
In Railties (the core code of Rails itself) the biggest changes are in the
config.gems
mechanism.
To avoid deployment issues and make Rails applications more self-contained,
it's possible to place copies of all of the gems that your Rails
application requires in /vendor/gems
. This capability first
appeared in Rails 2.1, but it's much more flexible and robust in Rails
2.2, handling complicated dependencies between gems. Gem management in
Rails includes these commands:
config.gem gem_name
in your
config/environment.rb
file
rake gems
to list all configured gems, as well as whether they
(and their dependencies) are installed, frozen, or framework (framework
gems are those loaded by Rails before the gem dependency code is executed;
such gems cannot be frozen)
rake gems:install
to install missing gems to the computer
rake gems:unpack
to place a copy of the required gems into
/vendor/gems
rake gems:unpack:dependencies
to get copies of the required
gems and their dependencies into /vendor/gems
rake gems:build
to build any missing native extensions
rake gems:refresh_specs
to bring vendored gems created with
Rails 2.1 into alignment with the Rails 2.2 way of storing them
You can unpack or install a single gem by specifying
GEM=gem_name
on the command line.
Lead Contributor: Matt Jones
More information:
If you're a fan of the Thin web server, you'll be
happy to know that script/server
now supports Thin directly.
script/plugin install <plugin> -r
<revision>
now works with git-based as well as
svn-based plugins.
script/console
now supports a --debugger
option
Instructions for setting up a continuous integration server to build Rails itself are included in the Rails source
rake notes:custom ANNOTATION=MYFLAG
lets you list out custom
annotations.
Wrapped Rails.env
in StringInquirer
so you can do
Rails.env.development?
To eliminate deprecation warnings and properly handle gem dependencies, Rails now requires rubygems 1.3.1 or higher.
A few pieces of older code are deprecated in this release:
Rails::SecretKeyGenerator
has been replaced by
ActiveSupport::SecureRandom
render_component
is deprecated. There's a render_components
plugin available if you need this functionality.
Implicit local assignments when rendering partials has been deprecated.
def partial_with_implicit_local_assignment @customer = Customer.new("Marcel") render :partial => "customer" end
Previously the above code made available a local variable called
customer
inside the partial 'customer'. You should
explicitly pass all the variables via :locals hash now.
country_select
has been removed. See the deprecation
page for more information and a plugin replacement.
ActiveRecord::Base.allow_concurrency
no longer has any effect.
ActiveRecord::Errors.default_error_messages
has been
deprecated in favor of
I18n.translate('activerecord.errors.messages')
The %s
and %d
interpolation syntax for
internationalization is deprecated.
String#chars
has been deprecated in favor of
String#mb_chars
.
Durations of fractional months or fractional years are deprecated. Use
Ruby's core Date
and Time
class arithmetic
instead.
Request#relative_url_root
is deprecated. Use
ActionController::Base.relative_url_root
instead.
Release notes compiled by Mike Gunderloy