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
   

   View Slide

2. 4.0
   

   View Slide

3. Question?
   

   View Slide

4. #rails4
   Tweet with this hashtag
   

   View Slide

5. Stats
   

   View Slide

6. 5,863 Commits
   62,684 +
   64,585 –
   

   View Slide

7. $ git log 9d6e52b...master |\
   pipe> sort | uniq | wc -l
   683
   683 Contributors
   

   View Slide

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
   

   View Slide

9. Deprecations
   ActiveRecord::SessionStore
   Old Dynamic Finders
   ActiveResource
   .scoped()
   Old Hash Finders
   Eager Evaluated Scope
   Rails Plugins
   

   View Slide

10. Release Note
    http://edgeguides.rubyonrails.org/4_0_release_notes.html
    

    View Slide

11. Notable Changes
    

    View Slide

12. Strong Parameters
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

16. # app/controllers/users_controller.rb
    class UsersController < ApplicationController
    def create
    @user = User.create!(params[:user])
    redirect_to @user
    end
    end
    

    View Slide

17. # app/controllers/users_controller.rb
    class UsersController < ApplicationController
    def create
    @user = User.create!(params[:user])
    redirect_to @user
    end
    end
    #=> Raises ActiveModel::ForbiddenAttributes
    

    View Slide

18. params.require(:user).permit(:username, :password,
    :password_confirmation)
    

    View Slide

19. params.require(:user).permit(:username, :password,
    :password_confirmation)
    

    View Slide

20. params.require(:user).permit(:username, :password,
    :password_confirmation)
    => POST /users
    Data: username=sikachu
    

    View Slide

21. params.require(:user).permit(:username, :password,
    :password_confirmation)
    => POST /users
    Data: username=sikachu
    <= 400 Bad Request
    

    View Slide

22. params.require(:user).permit(:username, :password,
    :password_confirmation)
    => POST /users
    Data: user[username]=sikachu
    

    View Slide

23. params.require(:user).permit(:username, :password,
    :password_confirmation)
    => POST /users
    Data: user[username]=sikachu
    <= 201 Created
    

    View Slide

24. params.require(:user).permit(:username, :password,
    :password_confirmation)
    

    View Slide

25. params.require(:user).permit(:username, :password,
    :password_confirmation)
    => POST /users
    Data: user[username]=sikachu&user[admin]=true
    

    View Slide

26. params.require(:user).permit(:username, :password,
    :password_confirmation)
    => POST /users
    Data: user[username]=sikachu&user[admin]=true
    <= 201 Created
    

    View Slide

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
    

    View Slide

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
    

    View Slide

29. Only works in controller
    @user.update_attributes(name: 'sikachu', admin: true)
    

    View Slide

30. Try Out Today!
    https://github.com/rails/strong_parameters
    Fully compatible with Rails 3.2.8
    

    View Slide

31. ActiveSupport::Queue
    

    View Slide

32. *Not Finalized Yet*
    At the time of this presentation ...
    

    View Slide

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
    

    View Slide

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)
    

    View Slide

35. Defaults
    • ActiveSupport::Queuing::Queue
    • Inherits from ::Queue (STDLIB)
    • ThreadConsumer will run the job in the
    background thread automatically.
    

    View Slide

36. Configurations
    # Default Container and Consumer
    config.queue = :asynchronous
    config.queue = :synchronous
    # Resque support in Resque 2.0.0.beta
    config.queue = :resque
    

    View Slide

37. Cache Digests
    

    View Slide

38. Cache Digests
    “Russian Doll Caching”
    

    View Slide

39. Russian Doll Caching
    @topic
    

    View Slide

40. Russian Doll Caching
    @post
    @topic
    

    View Slide

41. Russian Doll Caching
    @post
    @user
    @topic
    

    View Slide

42. <%# app/views/topics/show.html.erb %>
    <% cache [ "v1", @topic ] do %>
    <%= Topic.title %>
    <%= 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
    

    View Slide

43. @post
    @user
    @topic
    Update Template
    

    View Slide

44. @topic
    @user
    @post
    Update Template
    

    View Slide

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
    

    View Slide

46. @topic
    @user
    @post
    Update Template
    

    View Slide

47. @topic
    @user
    @post
    Update Template
    

    View Slide

48. @topic
    @user
    @post
    Update Template
    

    View Slide

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 %>
    

    View Slide

50. @topic
    @user
    @post
    Update Template
    

    View Slide

51. @user
    @topic
    @post
    Update Template
    

    View Slide

52. @user
    @topic
    @post
    Update Template
    

    View Slide

53. @user
    @topic
    @post
    Update Template
    

    View Slide

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 %>
    

    View Slide

55. Crazy!
    

    View Slide

56. Cache Digests
    

    View Slide

57. <%# app/views/topics/show.html.erb %>
    <% cache @topic do %>
    <%= Topic.title %>
    <%= 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
    

    View Slide

58. Generate MD5 of template and
    its dependencies as cache key
    views/topics/605816632-20120810191209/d9fb66b120b61f46707c67ab41d93cb2
    

    View Slide

59. Cache Expiration
    It just works!
    

    View Slide

60. $ rake cache_digests:dependencies TEMPLATE=topics/show
    [
    "posts/post"
    ]
    $ rake cache_digests:nested_dependencies TEMPLATE=topics/show
    [
    {
    "posts/post": [
    "users/user"
    ]
    }
    ]
    Inspect Dependencies
    

    View Slide

61. Try Out Today!
    https://github.com/rails/cache_digests
    Fully compatible with Rails 3.2.8
    

    View Slide

62. Cached Schema Dump
    

    View Slide

63. Cached Schema Dump
    Speed up Rails startup time
    

    View Slide

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
    

    View Slide

65. # config/environments/production.rb
    # Enabled by default
    config.active_record.use_schema_cache_dump = true
    

    View Slide

66. PATCH verb support
    

    View Slide

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.
    

    View Slide

68. <%= form_for @user do |f| %>
    
    
    
    
    
    ...
    

    View Slide

69. PUT /users/1
    PATCH /users/1
    => class UsersController < Appli
    def update
    end
    end
    

    View Slide

70. Routing Concern
    

    View Slide

71. Routing Concern
    Clean up duplicate routes
    

    View Slide

72. Before
    resources :messages do
    resources :comments
    end
    resources :posts do
    resources :comments
    resources :images, only: :index
    end
    

    View Slide

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]
    

    View Slide

74. ActiveRecord::Relation
    

    View Slide

75. Relation.first
    Relation.last
    

    View Slide

76. Relation.first
    Relation.last
    Always return record ordered by id
    

    View Slide

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
    

    View Slide

78. Relation.all
    

    View Slide

79. Relation.all
    Always return ActiveRecord::Relation object
    

    View Slide

80. Relation.all
    User.all
    # => #, #, ...]>
    User.to_a
    # => [#, #, ...]
    

    View Slide

81. Relation.none
    

    View Slide

82. Relation.none
    Returns ActiveRecord::NullRelation
    

    View Slide

83. Relation.none
    Still chainable!
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

88. Relation._____!
    

    View Slide

89. Relation._____!
    Mutates current relation
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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!
    

    View Slide

93. Deprecations
    

    View Slide

94. AR::Base.scoped
    

    View Slide

95. AR::Base.scoped
    Removed
    

    View Slide

96. AR::Base.scoped
    Use Model.all instead
    

    View Slide

97. Dynamic Finder
    Methods
    

    View Slide

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
    

    View Slide

99. Bring Back
    gem 'activerecord-deprecated_finders',
    github: 'rails/activerecord-deprecated_finders'
    External dependency in Rails 4.0
    (Remove in Rails 4.1)
    

    View Slide

100. Hash-based Finders
     

     View Slide

101. User.find(:first)
     User.find(:last, :order => 'id')
     User.find(:all, :conditions => { :active => true })
     

     View Slide

102. Bring Back
     gem 'activerecord-deprecated_finders',
     github: 'rails/activerecord-deprecated_finders'
     External dependency in Rails 4.0
     (Remove in Rails 4.1)
     

     View Slide

103. Eager Evaluated Scope
     

     View Slide

104. class User < ActiveRecord::Base
     scope :recent, where('created_at >= ?', 1.week.ago)
     end
     

     View Slide

105. class User < ActiveRecord::Base
     scope :recent, where('created_at >= ?', 1.week.ago)
     end
     

     View Slide

106. class User < ActiveRecord::Base
     scope :recent, where('created_at >= ?', 1.week.ago)
     end
     

     View Slide

107. Scope now requires a lambda
     

     View Slide

108. class User < ActiveRecord::Base
     scope :recent, -> { where('created_at >= ?', 1.week.ago) }
     end
     

     View Slide

109. ActiveRecord::SessionStore
     

     View Slide

110. ActiveRecord::SessionStore
     Extracted as a gem
     

     View Slide

111. gem 'activerecord-session_store',
     github: 'rails/activerecord_session_store'
     https://github.com/rails/activerecord-session_store
     

     View Slide

112. ActiveResource
     

     View Slide

113. ActiveResource
     Extracted as a gem
     

     View Slide

114. gem 'activeresource'
     https://github.com/rails/activeresource
     

     View Slide

115. Rails::Plugin
     

     View Slide

116. Rails::Plugin
     Removed
     

     View Slide

117. • Move it to your lib/ directory
     • Make it as a gem
     

     View Slide

118. New Deprecation Policy
     

     View Slide

119. SemVer
     Semantic Versioning
     

     View Slide

120. SemVer
     Semantic Versioning
     

     View Slide

121. Ver
     

     View Slide

122. Rails 3.1.x
     End of Life
     

     View Slide

123. Rails 3.2.x
     Some Deprecation Warnings
     (Support Until Rails 4.1.0 Comes Out)
     

     View Slide

124. Rails 4.0.0
     Deprecation Warnings
     

     View Slide

125. Rails 4.1.0
     Remove Deprecated Features
     

     View Slide

126. Smooth Upgrade
     From Rails 3.2.x to Rails 4.0.0
     

     View Slide

127. Release Candidate?
     

     View Slide

128. Release Candidate?
     Soon!
     

     View Slide

129. Try Now!
     # Gemfile
     # gem 'rails', '3.2.8'
     gem 'rails', github: 'rails/rails'
     $ bundle update
     

     View Slide

130. Report Bugs
     https://github.com/rails/rails/issues
     

     View Slide

131. Learn
     https://learn.thoughtbot.com/rails
     

     View Slide

132. Thank you!
     Prem Sichanugrist
     https://github.com/sikachu
     @sikachu
     Questions: #rails4
     

     View Slide