What to expect in Rails 4.0

The 4.0 release of Ruby on Rails is right around the corner. I'm going to highlight some of the new features and changes in the newest version of Rails, as well as features that will be removed or deprecated in Rails core.

(Note: The content of this slide may not reflect the final version of the release.)

Presented at BostonRB on September 11, 2012. Video is available at http://bostonrb.org/presentations/what-to-expect-in-rails-40.

Transcript

1. What to expect in Rails 4.0
2. 4.0
3. Question?
4. #rails4 Tweet with this hashtag
5. Stats
6. 5,863 Commits 62,684 + 64,585 –
7. $ git log 9d6e52b...master |\ pipe> sort | uniq | wc -l 683 683 Contributors
8. New Features Strong Parameters Null Relation Rails Queue Russian Doll Caching Relation#inspect Schema Cache Dump Routing Concern HTML5 tag helpers HTTP PATCH {asset}_url helpers .first and .last now have order() defined Scope mutation config.eager_load replaces threadsafe! Relation#pluck takes multiple arguments
9. Deprecations ActiveRecord::SessionStore Old Dynamic Finders ActiveResource .scoped() Old Hash Finders Eager Evaluated Scope Rails Plugins
10. Release Note http://edgeguides.rubyonrails.org/4_0_release_notes.html
11. Notable Changes
12. Strong Parameters
13. Strong Parameters • Replaces attr_accessor and attr_protected • Will be extracted as a gem (Dependency of Rails 4.0) • Moves parameters filtering concern to controller
14. # app/models/user.rb class User < ActiveRecord::Base attr_accessible :username, :password, :password_confirmation end # app/controllers/users_controller.rb class UsersController < ApplicationController def create @user = User.create!(params[:user]) redirect_to @user end end
15. # app/models/user.rb class User < ActiveRecord::Base; end # app/controllers/users_controller.rb class UsersController < ApplicationController def create @user = User.create!(user_params) redirect_to @user end private def user_params params.require(:user).permit(:username, :password, :password_confirmation) end end
16. # app/controllers/users_controller.rb class UsersController < ApplicationController def create @user = User.create!(params[:user]) redirect_to @user end end
17. # app/controllers/users_controller.rb class UsersController < ApplicationController def create @user = User.create!(params[:user]) redirect_to @user end end #=> Raises ActiveModel::ForbiddenAttributes
18. params.require(:user).permit(:username, :password, :password_confirmation)
19. params.require(:user).permit(:username, :password, :password_confirmation)
20. params.require(:user).permit(:username, :password, :password_confirmation) => POST /users Data: username=sikachu
21. params.require(:user).permit(:username, :password, :password_confirmation) => POST /users Data: username=sikachu <= 400 Bad Request
22. params.require(:user).permit(:username, :password, :password_confirmation) => POST /users Data: user[username]=sikachu
23. params.require(:user).permit(:username, :password, :password_confirmation) => POST /users Data: user[username]=sikachu <= 201 Created
24. params.require(:user).permit(:username, :password, :password_confirmation)
25. params.require(:user).permit(:username, :password, :password_confirmation) => POST /users Data: user[username]=sikachu&user[admin]=true
26. params.require(:user).permit(:username, :password, :password_confirmation) => POST /users Data: user[username]=sikachu&user[admin]=true <= 201 Created
27. params.require(:user).permit(:username, :password, :password_confirmation) => POST /users Data: user[username]=sikachu&user[admin]=true <= 201 Created irb> User.find_by_username('sikachu').admin? => false
28. Easier multi-roles filtering # app/controllers/users_controller.rb class UsersController < ApplicationController def user_params params.require(:user).permit(:username, :password, :password_confirmation) end end # app/controllers/admin/users_controller.rb class Admin::UsersController < ApplicationController def user_params params.require(:user).permit(User.attribute_names) end end
29. Only works in controller @user.update_attributes(name: 'sikachu', admin: true)
30. Try Out Today! https://github.com/rails/strong_parameters Fully compatible with Rails 3.2.8
31. ActiveSupport::Queue
32. *Not Finalized Yet* At the time of this presentation ...
33. Job # Requires an object that respond to #run class UserRegistrationMailerJob < Struct.new(:user_id) def run user = User.find(user_id) UserMailer.welcome_email(user).deliver end end
34. Queue it! # Pass in an object that respond to #run class UserRegistrationMailerJob < Struct.new(:user_id) def run user = User.find(user_id) UserMailer.welcome_email(user).deliver end end # Usage Rails.queue.push UserRegistrationMailerJob(@user.id)
35. Defaults • ActiveSupport::Queuing::Queue • Inherits from ::Queue (STDLIB) • ThreadConsumer will run the job in the background thread automatically.
36. Configurations # Default Container and Consumer config.queue = :asynchronous config.queue = :synchronous # Resque support in Resque 2.0.0.beta config.queue = :resque
37. Cache Digests
38. Cache Digests “Russian Doll Caching”
39. Russian Doll Caching @topic
40. Russian Doll Caching @post @topic
41. Russian Doll Caching @post @user @topic
42. <%# app/views/topics/show.html.erb %> <% cache [ "v1", @topic ] do %> <h1><%= Topic.title %></h1> <%= render @topic.posts %> <% end %> <%# app/views/posts/_post.html.erb %> <% cache [ "v1", post ] do %> <%= render post.author %> <%= post.content %> <% end %> <%# app/views/users/_user.html.erb %> <% cache [ "v1", user ] do %> Posted by <%= user.name %> <% end %> Russian Doll Caching
43. @post @user @topic Update Template
44. @topic @user @post Update Template
45. <%# app/views/topics/show.html.erb %> <% cache [ "v2", @topic ] do %> ... <% end %> <%# app/views/posts/_post.html.erb %> <% cache [ "v1", post ] do %> ... <% end %> <%# app/views/users/_user.html.erb %> <% cache [ "v1", user ] do %> ... <% end %> Expire Cache
46. @topic @user @post Update Template
47. @topic @user @post Update Template
48. @topic @user @post Update Template
49. Expire Cache <%# app/views/topics/show.html.erb %> <% cache [ "v3", @topic ] do %> ... <% end %> <%# app/views/posts/_post.html.erb %> <% cache [ "v2", post ] do %> ... <% end %> <%# app/views/users/_user.html.erb %> <% cache [ "v1", user ] do %> ... <% end %>
50. @topic @user @post Update Template
51. @user @topic @post Update Template
52. @user @topic @post Update Template
53. @user @topic @post Update Template
54. Expire Cache <%# app/views/topics/show.html.erb %> <% cache [ "v4", @topic ] do %> ... <% end %> <%# app/views/posts/_post.html.erb %> <% cache [ "v3", post ] do %> ... <% end %> <%# app/views/users/_user.html.erb %> <% cache [ "v2", user ] do %> ... <% end %>
55. Crazy!
56. Cache Digests
57. <%# app/views/topics/show.html.erb %> <% cache @topic do %> <h1><%= Topic.title %></h1> <%= render @topic.posts %> <% end %> <%# app/views/posts/_post.html.erb %> <% cache post do %> <%= render post.author %> <%= post.content %> <% end %> <%# app/views/users/_user.html.erb %> <% cache user do %> Posted by <%= user.name %> <% end %> Your Template
58. Generate MD5 of template and its dependencies as cache key views/topics/605816632-20120810191209/d9fb66b120b61f46707c67ab41d93cb2
59. Cache Expiration It just works!
60. $ rake cache_digests:dependencies TEMPLATE=topics/show [ "posts/post" ] $ rake cache_digests:nested_dependencies TEMPLATE=topics/show [ { "posts/post": [ "users/user" ] } ] Inspect Dependencies
61. Try Out Today! https://github.com/rails/cache_digests Fully compatible with Rails 3.2.8
62. Cached Schema Dump
63. Cached Schema Dump Speed up Rails startup time
64. $ bundle exec rake db:schema:cache:dump => generate db/schema_cache.dump # You might want to add this to your repository $ RAILS_ENV=production bundle exec rails server => use db/schema_cache.dump
65. # config/environments/production.rb # Enabled by default config.active_record.use_schema_cache_dump = true
66. PATCH verb support
67. RFC 5789 • The PUT method is already defined to overwrite a resource with a complete new body, and cannot be reused to do partial changes. Otherwise, proxies and caches, and even clients and servers, may get confused as to the result of the operation. • This specification defines the new HTTP/1.1 method, PATCH, which is used to apply partial modifications to a resource.
68. <%= form_for @user do |f| %> <form action="/users/1" method="post" ... > <div style="margin:0;padding:0;display:inline"> <input name="utf8" type="hidden" value="&#x2713;" /> <input name="_method" type="hidden" value="patch" /> <input name="authenticity_token" ... /> ...
69. PUT /users/1 PATCH /users/1 => class UsersController < Appli def update end end
70. Routing Concern
71. Routing Concern Clean up duplicate routes
72. Before resources :messages do resources :comments end resources :posts do resources :comments resources :images, only: :index end
73. After concern :commentable do resources :comments end concern :image_attachables do resources :images, only: :index end resources :messages, concerns: :commentable resources :posts, concerns: [:commentable, : image_attachables]
74. ActiveRecord::Relation
75. Relation.first Relation.last
76. Relation.first Relation.last Always return record ordered by id
77. Relation.first Relation.last # User.first SELECT “users”.* FROM “users” ORDER BY id LIMIT 1 # User.last SELECT “users”.* FROM “users” ORDER BY id DESC LIMIT 1
78. Relation.all
79. Relation.all Always return ActiveRecord::Relation object
80. Relation.all User.all # => #<ActiveRecord::Relation [#<User ...>, #<User ...>, ...]> User.to_a # => [#<User ...>, #<User ...>, ...]
81. Relation.none
82. Relation.none Returns ActiveRecord::NullRelation
83. Relation.none Still chainable!
84. # app/controllers/users_controller.rb class UsersController < ApplicationController def index @users = Users.name_starts_with(params[:prefix]). order(:name).paginate(params[:page], :per_page => 15) end end # app/models/user.rb class User < ActiveRecord::Base def self.starts_with(prefix) if prefix.present? where('name LIKE ?', "#{prefix}%") else # ... ? ... end end end
85. # app/controllers/users_controller.rb class UsersController < ApplicationController def index @users = Users.name_starts_with(params[:prefix]). order(:name).paginate(params[:page], :per_page => 15) end end # app/models/user.rb class User < ActiveRecord::Base def self.starts_with(prefix) if prefix.present? where('name LIKE ?', "#{prefix}%") else [] end end end
86. # app/controllers/users_controller.rb class UsersController < ApplicationController def index @users = Users.name_starts_with(params[:prefix]). order(:name).paginate(params[:page], :per_page => 15) end end # app/models/user.rb class User < ActiveRecord::Base def self.starts_with(prefix) if prefix.present? where('name LIKE ?', "#{prefix}%") else [] #=> NoMethodError when calling #order end end end
87. # app/controllers/users_controller.rb class UsersController < ApplicationController def index @users = Users.name_starts_with(params[:prefix]). order(:name).paginate(params[:page], :per_page => 15) end end # app/models/user.rb class User < ActiveRecord::Base def self.starts_with(prefix) if prefix.present? where('name LIKE ?', "#{prefix}%") else none end end end
88. Relation._____!
89. Relation._____! Mutates current relation
90. # app/controller/users_controller.rb class UsersController < ApplicationController def index @users = User @users = @users.where(:id => params[:id]) if params[:id] @users = @users.includes(:comments) if params[:comments] @users = @users.order(:name) end end
91. # app/controller/users_controller.rb class UsersController < ApplicationController def index @users = User @users.where!(:id => params[:id]) if params[:id] @users.includes!(:comments) if params[:comments] @users.order!(:name) end end
92. bind! create_with! eager_load! extending! from! group! having! includes! joins! limit! lock! offset! order! preload! readonly! references! reorder! reverse_order! select! uniq! where!
93. Deprecations
94. AR::Base.scoped
95. AR::Base.scoped Removed
96. AR::Base.scoped Use Model.all instead
97. Dynamic Finder Methods
98. find_all_by_... => where(...) find_last_by_... => where(...).last scoped_by_... => where(...) find_or_create_by_... => where(...).first_or_create find_or_create_by_...! => where(...).first_or_create! find_or_initialize_by_... => where(...).first_or_initialize
99. Bring Back gem 'activerecord-deprecated_finders', github: 'rails/activerecord-deprecated_finders' External dependency in Rails 4.0 (Remove in Rails 4.1)
100. Hash-based Finders
101. User.find(:first) User.find(:last, :order => 'id') User.find(:all, :conditions => { :active => true })
102. Bring Back gem 'activerecord-deprecated_finders', github: 'rails/activerecord-deprecated_finders' External dependency in Rails 4.0 (Remove in Rails 4.1)
103. Eager Evaluated Scope
104. class User < ActiveRecord::Base scope :recent, where('created_at >= ?', 1.week.ago) end
105. class User < ActiveRecord::Base scope :recent, where('created_at >= ?', 1.week.ago) end
106. class User < ActiveRecord::Base scope :recent, where('created_at >= ?', 1.week.ago) end
107. Scope now requires a lambda
108. class User < ActiveRecord::Base scope :recent, -> { where('created_at >= ?', 1.week.ago) } end
109. ActiveRecord::SessionStore
110. ActiveRecord::SessionStore Extracted as a gem
111. gem 'activerecord-session_store', github: 'rails/activerecord_session_store' https://github.com/rails/activerecord-session_store
112. ActiveResource
113. ActiveResource Extracted as a gem
114. gem 'activeresource' https://github.com/rails/activeresource
115. Rails::Plugin
116. Rails::Plugin Removed
117. • Move it to your lib/ directory • Make it as a gem
118. New Deprecation Policy
119. SemVer Semantic Versioning
120. SemVer Semantic Versioning
121. Ver
122. Rails 3.1.x End of Life
123. Rails 3.2.x Some Deprecation Warnings (Support Until Rails 4.1.0 Comes Out)
124. Rails 4.0.0 Deprecation Warnings
125. Rails 4.1.0 Remove Deprecated Features
126. Smooth Upgrade From Rails 3.2.x to Rails 4.0.0
127. Release Candidate?
128. Release Candidate? Soon!
129. Try Now! # Gemfile # gem 'rails', '3.2.8' gem 'rails', github: 'rails/rails' $ bundle update
130. Report Bugs https://github.com/rails/rails/issues
131. Learn https://learn.thoughtbot.com/rails
132. Thank you! Prem Sichanugrist https://github.com/sikachu @sikachu Questions: #rails4