Froze rails gems
[depot.git] / vendor / rails / railties / doc / guides / source / 2_2_release_notes.txt
1 Ruby on Rails 2.2 Release Notes
2 ===============================
3
4 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 link:http://github.com/rails/rails/commits/master[list of commits] in the main Rails repository on GitHub.
5
6 Along with Rails, 2.2 marks the launch of the link:http://guides.rubyonrails.org/[Ruby on Rails Guides], the first results of the ongoing link:http://hackfest.rubyonrails.org/guide[Rails Guides hackfest]. This site will deliver high-quality documentation of the major features of Rails.
7
8 == Infrastructure
9
10 Rails 2.2 is a significant release for the infrastructure that keeps Rails humming along and connected to the rest of the world.
11
12 === Internationalization
13
14 Rails 2.2 supplies an easy system for internationalization (or i18n, for those of you tired of typing).
15
16 * Lead Contributors: Rails i18 Team
17 * More information :
18 - link:http://rails-i18n.org[Official Rails i18 website]
19 - link:http://www.artweb-design.de/2008/7/18/finally-ruby-on-rails-gets-internationalized[Finally. Ruby on Rails gets internationalized]
20 - link:http://i18n-demo.phusion.nl[Localizing Rails : Demo application]
21
22 === Compatibility with Ruby 1.9 and JRuby
23
24 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.
25
26 == Documentation
27
28 The internal documentation of Rails, in the form of code comments, has been improved in numerous places. In addition, the link:http://guides.rubyonrails.org/[Ruby on Rails Guides] project is the definitive source for information on major Rails components. In its first official release, the Guides page includes:
29
30 * link:http://guides.rubyonrails.org/getting_started_with_rails.html[Getting Started with Rails]
31 * link:http://guides.rubyonrails.org/migrations.html[Rails Database Migrations]
32 * link:http://guides.rubyonrails.org/association_basics.html[Active Record Associations]
33 * link:http://guides.rubyonrails.org/finders.html[Active Record Finders]
34 * link:http://guides.rubyonrails.org/layouts_and_rendering.html[Layouts and Rendering in Rails]
35 * link:http://guides.rubyonrails.org/form_helpers.html[Action View Form Helpers]
36 * link:http://guides.rubyonrails.org/routing_outside_in.html[Rails Routing from the Outside In]
37 * link:http://guides.rubyonrails.org/actioncontroller_basics.html[Basics of Action Controller]
38 * link:http://guides.rubyonrails.org/caching_with_rails.html[Rails Caching]
39 * link:http://guides.rubyonrails.org/testing_rails_applications.html[Testing Rails Applications]
40 * link:http://guides.rubyonrails.org/security.html[Securing Rails Applications]
41 * link:http://guides.rubyonrails.org/debugging_rails_applications.html[Debugging Rails Applications]
42 * link:http://guides.rubyonrails.org/benchmarking_and_profiling.html[Benchmarking and Profiling Rails Applications]
43 * link:http://guides.rubyonrails.org/creating_plugins.html[The Basics of Creating Rails Plugins]
44
45 All told, the Guides provide tens of thousands of words of guidance for beginning and intermediate Rails developers.
46
47 If you want to generate these guides locally, inside your application:
48
49 [source, ruby]
50 -------------------------------------------------------
51 rake doc:guides
52 -------------------------------------------------------
53
54 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.
55
56 * Lead Contributors: link:http://guides.rails.info/authors.html[Rails Documentation Team]
57 * Major contributions from link:http://advogato.org/person/fxn/diary.html[Xavier Noria] and link:http://izumi.plan99.net/blog/[Hongli Lai].
58 * More information:
59 - link:http://hackfest.rubyonrails.org/guide[Rails Guides hackfest]
60 - link:http://weblog.rubyonrails.org/2008/5/2/help-improve-rails-documentation-on-git-branch[Help improve Rails documentation on Git branch]
61
62 == Better integration with HTTP : Out of the box ETag support
63
64 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.
65
66 [source, ruby]
67 -------------------------------------------------------
68 class ArticlesController < ApplicationController
69 def show_with_respond_to_block
70 @article = Article.find(params[:id])
71
72 # If the request sends headers that differs from the options provided to stale?, then
73 # the request is indeed stale and the respond_to block is triggered (and the options
74 # to the stale? call is set on the response).
75 #
76 # If the request headers match, then the request is fresh and the respond_to block is
77 # not triggered. Instead the default render will occur, which will check the last-modified
78 # and etag headers and conclude that it only needs to send a "304 Not Modified" instead
79 # of rendering the template.
80 if stale?(:last_modified => @article.published_at.utc, :etag => @article)
81 respond_to do |wants|
82 # normal response processing
83 end
84 end
85 end
86
87 def show_with_implied_render
88 @article = Article.find(params[:id])
89
90 # Sets the response headers and checks them against the request, if the request is stale
91 # (i.e. no match of either etag or last-modified), then the default render of the template happens.
92 # If the request is fresh, then the default render will return a "304 Not Modified"
93 # instead of rendering the template.
94 fresh_when(:last_modified => @article.published_at.utc, :etag => @article)
95 end
96 end
97 -------------------------------------------------------
98
99 == Thread Safety
100
101 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.
102
103 To enable multithreaded dispatching in production mode of your application, add the following line in your +config/environments/production.rb+:
104
105 [source, ruby]
106 -------------------------------------------------------
107 config.threadsafe!
108 -------------------------------------------------------
109
110 * More information :
111 - link:http://m.onkey.org/2008/10/23/thread-safety-for-your-rails[Thread safety for your Rails]
112 - link:http://weblog.rubyonrails.org/2008/8/16/josh-peek-officially-joins-the-rails-core[Thread safety project announcement]
113 - link:http://blog.headius.com/2008/08/qa-what-thread-safe-rails-means.html[Q/A: What Thread-safe Rails Means]
114
115 == Active Record
116
117 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.
118
119 === Transactional Migrations
120
121 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.
122
123 * Lead Contributor: link:http://adam.blog.heroku.com/[Adam Wiggins]
124 * More information:
125 - link:http://adam.blog.heroku.com/past/2008/9/3/ddl_transactions/[DDL Transactions]
126 - link:http://db2onrails.com/2008/11/08/a-major-milestone-for-db2-on-rails/[A major milestone for DB2 on Rails]
127
128 === Connection Pooling
129
130 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.
131
132 [source, ruby]
133 -------------------------------------------------------
134 development:
135 adapter: mysql
136 username: root
137 database: sample_development
138 pool: 10
139 wait_timeout: 10
140 -------------------------------------------------------
141
142 * Lead Contributor: link:http://blog.nicksieger.com/[Nick Sieger]
143 * More information:
144 - link:http://ryandaigle.com/articles/2008/9/7/what-s-new-in-edge-rails-connection-pools[What's New in Edge Rails: Connection Pools]
145
146 === Hashes for Join Table Conditions
147
148 You can now specify conditions on join tables using a hash. This is a big help if you need to query across complex joins.
149
150 [source, ruby]
151 -------------------------------------------------------
152 class Photo < ActiveRecord::Base
153 belongs_to :product
154 end
155
156 class Product < ActiveRecord::Base
157 has_many :photos
158 end
159
160 # Get all products with copyright-free photos:
161 Product.all(:joins => :photos, :conditions => { :photos => { :copyright => false }})
162 -------------------------------------------------------
163
164 * More information:
165 - link:http://ryandaigle.com/articles/2008/7/7/what-s-new-in-edge-rails-easy-join-table-conditions[What's New in Edge Rails: Easy Join Table Conditions]
166
167 === New Dynamic Finders
168
169 Two new sets of methods have been added to Active Record's dynamic finders family.
170
171 ==== +find_last_by_<attribute>+
172
173 The +find_last_by_<attribute>+ method is equivalent to +Model.last(:conditions => {:attribute => value})+
174
175 [source, ruby]
176 -------------------------------------------------------
177 # Get the last user who signed up from London
178 User.find_last_by_city('London')
179 -------------------------------------------------------
180
181 * Lead Contributor: link:http://www.workingwithrails.com/person/9147-emilio-tagua[Emilio Tagua]
182
183 ==== +find_by_<attribute>!+
184
185 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.
186
187 [source, ruby]
188 -------------------------------------------------------
189 # Raise ActiveRecord::RecordNotFound exception if 'Moby' hasn't signed up yet!
190 User.find_by_name!('Moby')
191 -------------------------------------------------------
192
193 * Lead Contributor: link:http://blog.hasmanythrough.com[Josh Susser]
194
195 === Associations Respect Private/Protected Scope
196
197 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.
198
199 * Lead Contributor: Adam Milligan
200 * More information:
201 - link:http://afreshcup.com/2008/10/24/rails-22-change-private-methods-on-association-proxies-are-private/[Rails 2.2 Change: Private Methods on Association Proxies are Private]
202
203 === Other ActiveRecord Changes
204
205 * +rake db:migrate:redo+ now accepts an optional VERSION to target that specific migration to redo
206 * Set +config.active_record.timestamped_migrations = false+ to have migrations with numeric prefix instead of UTC timestamp.
207 * Counter cache columns (for associations declared with +:counter_cache => true+) do not need to be initialized to zero any longer.
208 * +ActiveRecord::Base.human_name+ for an internationalization-aware humane translation of model names
209
210 == Action Controller
211
212 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.
213
214 === Shallow Route Nesting
215
216 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.
217
218 [source, ruby]
219 -------------------------------------------------------
220 map.resources :publishers, :shallow => true do |publisher|
221 publisher.resources :magazines do |magazine|
222 magazine.resources :photos
223 end
224 end
225 -------------------------------------------------------
226
227 This will enable recognition of (among others) these routes:
228
229 -------------------------------------------------------
230 /publishers/1 ==> publisher_path(1)
231 /publishers/1/magazines ==> publisher_magazines_path(1)
232 /magazines/2 ==> magazine_path(2)
233 /magazines/2/photos ==> magazines_photos_path(2)
234 /photos/3 ==> photo_path(3)
235 -------------------------------------------------------
236
237 * Lead Contributor: link:http://www.unwwwired.net/[S. Brent Faulkner]
238 * More information:
239 - link:http://guides.rails.info/routing/routing_outside_in.html#_nested_resources[Rails Routing from the Outside In]
240 - link:http://ryandaigle.com/articles/2008/9/7/what-s-new-in-edge-rails-shallow-routes[What's New in Edge Rails: Shallow Routes]
241
242 === Method Arrays for Member or Collection Routes
243
244 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:
245
246 [source, ruby]
247 -------------------------------------------------------
248 map.resources :photos, :collection => { :search => [:get, :post] }
249 -------------------------------------------------------
250
251 * Lead Contributor: link:http://brennandunn.com/[Brennan Dunn]
252
253 === Resources With Specific Actions
254
255 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.
256
257 [source, ruby]
258 -------------------------------------------------------
259 map.resources :photos, :only => [:index, :show]
260 map.resources :products, :except => :destroy
261 -------------------------------------------------------
262
263 * Lead Contributor: link:http://experthuman.com/[Tom Stuart]
264
265 === Other Action Controller Changes
266
267 * You can now easily link:http://m.onkey.org/2008/7/20/rescue-from-dispatching[show a custom error page] for exceptions raised while routing a request.
268 * 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.user_accept_header = true+.
269 * Benchmarking numbers are now reported in milliseconds rather than tiny fractions of seconds
270 * Rails now supports HTTP-only cookies (and uses them for sessions), which help mitigate some cross-site scripting risks in newer browsers.
271 * +redirect_to+ now fully supports URI schemes (so, for example, you can redirect to a svn+ssh: URI).
272 * +render+ now supports a +:js+ option to render plain vanilla javascript with the right mime type.
273 * Request forgery protection has been tightened up to apply to HTML-formatted content requests only.
274 * 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+.
275
276 == Action View
277
278 * +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.
279 * The included Prototype javascript library has been upgraded to version 1.6.0.3.
280 * +RJS#page.reload+ to reload the browser's current location via javascript
281 * The +atom_feed+ helper now takes an +:instruct+ option to let you insert XML processing instructions.
282
283 == Action Mailer
284
285 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+.
286
287 * More information:
288 - link:http://ryandaigle.com/articles/2008/9/7/what-s-new-in-edge-rails-mailer-layouts[What's New in Edge Rails: Mailer Layouts]
289
290 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.
291
292 == Active Support
293
294 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.
295
296 === Memoization
297
298 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:
299
300 [source, ruby]
301 -------------------------------------------------------
302 def full_name
303 @full_name ||= "#{first_name} #{last_name}"
304 end
305 -------------------------------------------------------
306
307 Memoization lets you handle this task in a declarative fashion:
308
309 [source, ruby]
310 -------------------------------------------------------
311 extend ActiveSupport::Memoizable
312
313 def full_name
314 "#{first_name} #{last_name}"
315 end
316 memoize :full_name
317 -------------------------------------------------------
318
319 Other features of memoization include +unmemoize+, +unmemoize_all+, and +memoize_all+ to turn memoization on or off.
320
321 * Lead Contributor: link:http://joshpeek.com/[Josh Peek]
322 * More information:
323 - link:http://ryandaigle.com/articles/2008/7/16/what-s-new-in-edge-rails-memoization[What's New in Edge Rails: Easy Memoization]
324 - link:http://www.railway.at/articles/2008/09/20/a-guide-to-memoization[Memo-what? A Guide to Memoization]
325
326 === +each_with_object+
327
328 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.
329
330 [source, ruby]
331 -------------------------------------------------------
332 %w(foo bar).each_with_object({}) { |str, hsh| hsh[str] = str.upcase } #=> {'foo' => 'FOO', 'bar' => 'BAR'}
333 -------------------------------------------------------
334
335 Lead Contributor: link:http://therealadam.com/[Adam Keys]
336
337 === Delegates With Prefixes
338
339 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:
340
341 [source, ruby]
342 -------------------------------------------------------
343 class Vendor < ActiveRecord::Base
344 has_one :account
345 delegate :email, :password, :to => :account, :prefix => true
346 end
347 -------------------------------------------------------
348
349 This will produce delegated methods +vendor#account_email+ and +vendor#account_password+. You can also specify a custom prefix:
350
351 [source, ruby]
352 -------------------------------------------------------
353 class Vendor < ActiveRecord::Base
354 has_one :account
355 delegate :email, :password, :to => :account, :prefix => :owner
356 end
357 -------------------------------------------------------
358
359 This will produce delegated methods +vendor#owner_email+ and +vendor#owner_password+.
360
361 Lead Contributor: link:http://workingwithrails.com/person/5830-daniel-schierbeck[Daniel Schierbeck]
362
363 === Other Active Support Changes
364
365 * Extensive updates to +ActiveSupport::Multibyte+, including Ruby 1.9 compatibility fixes.
366 * The addition of +ActiveSupport::Rescuable+ allows any class to mix in the +rescue_from+ syntax.
367 * +past?+, +today?+ and +future?+ for +Date+ and +Time+ classes to facilitate date/time comparisons.
368 * +Array#second+ through +Array#fifth+ as aliases for +Array#[1]+ through +Array#[4]+
369 * +Enumerable#many?+ to encapsulate +collection.size > 1+
370 * +Inflector#parameterize+ produces a URL-ready version of its input, for use in +to_param+.
371 * +Time#advance+ recognizes fractional days and weeks, so you can do +1.7.weeks.ago+, +1.5.hours.since+, and so on.
372 * The included TzInfo library has been upgraded to version 0.3.12.
373 * +ActiveSuport::StringInquirer+ gives you a pretty way to test for equality in strings: +ActiveSupport::StringInquirer.new("abc").abc? => true+
374
375 == Railties
376
377 In Railties (the core code of Rails itself) the biggest changes are in the +config.gems+ mechanism.
378
379 === +config.gems+
380
381 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:
382
383 * +config.gem _gem_name_+ in your +config/environment.rb+ file
384 * +rake gems+ to list all configured gems, as well as whether they (and their dependencies) are installed or frozen
385 * +rake gems:install+ to install missing gems to the computer
386 * +rake gems:unpack+ to place a copy of the required gems into +/vendor/gems+
387 * +rake gems:unpack:dependencies+ to get copies of the required gems and their dependencies into +/vendor/gems+
388 * +rake gems:build+ to build any missing native extensions
389 * +rake gems:refresh_specs+ to bring vendored gems created with Rails 2.1 into alignment with the Rails 2.2 way of storing them
390
391 You can unpack or install a single gem by specifying +GEM=_gem_name_+ on the command line.
392
393 * Lead Contributor: link:http://github.com/al2o3cr[Matt Jones]
394 * More information:
395 - link:http://ryandaigle.com/articles/2008/4/1/what-s-new-in-edge-rails-gem-dependencies[What's New in Edge Rails: Gem Dependencies]
396 - link:http://afreshcup.com/2008/10/25/rails-212-and-22rc1-update-your-rubygems/[Rails 2.1.2 and 2.2RC1: Update Your RubyGems]
397
398 === Other Railties Changes
399
400 * If you're a fan of the link:http://code.macournoyer.com/thin/[Thin] web server, you'll be happy to know that +script/server+ now supports Thin directly.
401 * +script/plugin install <plugin> -r <revision>+ now works with git-based as well as svn-based plugins.
402 * +script/console+ now supports a +--debugger+ option
403 * Instructions for setting up a continuous integration server to build Rails itself are included in the Rails source
404 * +rake notes:custom ANNOTATION=MYFLAG+ lets you list out custom annotations.
405 * Wrapped +Rails.env+ in +StringInquirer+ so you can do +Rails.env.development?+
406 * To eliminate deprecation warnings and properly handle gem dependencies, Rails now requires rubygems 1.3.1 or higher.
407
408 == Deprecated
409
410 A few pieces of older code are deprecated in this release:
411
412 * +Rails::SecretKeyGenerator+ has been replaced by +ActiveSupport::SecureRandom+
413 * +render_component+ is deprecated. There's a link:http://github.com/rails/render_component/tree/master[render_components plugin] available if you need this functionality.
414 * Implicit local assignments when rendering partials has been deprecated.
415
416 [source, ruby]
417 -------------------------------------------------------
418 def partial_with_implicit_local_assignment
419 @customer = Customer.new("Marcel")
420 render :partial => "customer"
421 end
422 -------------------------------------------------------
423
424 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.
425
426 * +country_select+ has been removed. See the link:http://www.rubyonrails.org/deprecation/list-of-countries[deprecation page] for more information and a plugin replacement.
427 * +ActiveRecord::Base.allow_concurrency+ no longer has any effect.
428 * +ActiveRecord::Errors.default_error_messages+ has been deprecated in favor of +I18n.translate('activerecord.errors.messages')+
429 * The +%s+ and +%d+ interpolation syntax for internationalization is deprecated.
430 * +String#chars+ has been deprecated in favor of +String#mb_chars+.
431 * Durations of fractional months or fractional years are deprecated. Use Ruby's core +Date+ and +Time+ class arithmetic instead.
432
433 == Credits
434
435 Release notes compiled by link:http://afreshcup.com[Mike Gunderloy]