This is the short talk I delivered at the Ruby Underground Meetup in Tel Aviv for the local Ruby user group about some of the changes and new features in R

1. What is new in
Rails 4?
Fabio Akita
@akitaonrails
codeminer42.com

2. Experimenting

3. git clone git://github.com/rails/
rails.git
ruby /path/to/rails/railties/bin/rails
new project --dev
(follow error messages)

4. Ruby 1.9.3

5. vendor/plugins

6. Deprecation
Policy

7. Page and Action Caching
Active Record Mass Assignment
Sanitizer
Active Record Session Store
Active Resource

8. Cache Digest
(aka Russian Doll Caching Scheme)

9. # app/views/projects/show.html.erb
<% cache [ "v1", project ] do %>
<h1>All documents</h1>
<%= render project.documents %>
<h1>All todolists</h1>
<%= render project.todolists %>
<% end %>
# app/views/documents/_document.html.erb
<% cache [ "v1", document ] do %>
My document: <%= document.name %>
<%= render document.comments %>
<% end %>
# app/views/todolists/_todolist.html.erb
<% cache [ "v1", todolist ] do %>
My todolist: <%= todolist.name %>
<%= render document.comments %>
<% end %>
# app/views/comments/_comment.html.erb
<% cache [ "v1", comment ] do %>
My comment: <%= comment.body %>
<% end %>

10. # app/views/projects/show.html.erb
<% cache [ "v1", project ] do %>
<h1>All documents</h1>
<%= render project.documents %>
<h1>All todolists</h1>
<%= render project.todolists %>
<% end %>
# app/views/documents/_document.html.erb
<% cache [ "v1", document ] do %>
My document: <%= document.name %>
<%= render document.comments %>
<% end %>
# app/views/todolists/_todolist.html.erb
<% cache [ "v1", todolist ] do %>
My todolist: <%= todolist.name %>
<%= render document.comments %>
<% end %>
# app/views/comments/_comment.html.erb
<% cache [ "v1", comment ] do %>
My comment: <%= comment.body %>
<% end %>

11. # app/views/projects/show.html.erb
<% cache project do %>
<h1>All documents</h1>
<%= render project.documents %>
<h1>All todolists</h1>
<%= render project.todolists %>
<% end %>
# app/views/documents/_document.html.erb
<% cache document do %>
My document: <%= document.name %>
<%= render document.comments %>
<% end %>
# app/views/todolists/_todolist.html.erb
<% cache todolist do %>
My todolist: <%= todolist.name %>
<%= render document.comments %>
<% end %>
# app/views/comments/_comment.html.erb
<% cache comment do %>
My comment: <%= comment.body %>
<% end %>

12. views/projects/
605816632-20120810191209/
d9fb66b120b61f46707c67ab41d
93cb2
(MD5 of the template file)

13. $ rake cache_digests:dependencies TEMPLATE=projects/show
[
"documents/document",
"todolists/todolist"
]
$ rake cache_digests:nested_dependencies TEMPLATE=projects/show
[
{
"documents/document": [
"comments/comment"
]
},
{
"todolists/todolist": [
"comments/comment"
]
}
]

14. render group_of_attachments
render @project.documents.published.ordered
render partial: 'attachments/attachment',
collection: group_of_attachments
render partial: 'documents/document',
collection: @project.documents.published.ordered

15. <%= render_sortable_todolists @project.todolists %>
<%# Template Dependency: todolists/todolist %>
<%= render_sortable_todolists @project.todolists %>

16. Page and Action Caching
Active Record Mass Assignment
Sanitizer
Active Record Session Store
Active Resource

17. Strong
Parameters

18. class Person < ActiveRecord::Base
attr_accessible :name, :age
validates_presence_of :name
validates_numericality_of :age
end

19. class Person < ActiveRecord::Base
attr_accessible :name, :age, :role
validates_presence_of :name
validates_numericality_of :age
validates_inclusion_of :role, in: %w(user admin)
end

20. class Person < ActiveRecord::Base
validates_presence_of :name
validates_numericality_of :age
validates_inclusion_of :role, in: %w(user admin)
end

21. class PeopleController < ActionController::Base
# ...
private
def person_params
params.require(:person).permit(:name, :age)
end
end

22. class PeopleController < ActionController::Base
def create
Person.create(params[:person])
end
# ActiveModel::ForbiddenAttributes
# ...
end

23. class PeopleController < ActionController::Base
def create
Person.create(person_params)
end
# ...
end

24. class PeopleController < ActionController::Base
# ...
def update
@person = current_account.people.find(params[:id])
redirect_to @person.tap { |person|
person.update_attributes!(person_params)
}
end
# ActionController::MissingParameter (400 Bad Request)
# ...
end

25. class PeopleController < ActionController::Base
# ...
private
def person_params
params.require(:person).permit(:name, :age)
end
end
class AdminController < ActionController::Base
# ...
private
def person_params
params.require(:person).permit(:name, :age, :role)
end
end

26. Page and Action Caching
Active Record Mass Assignment
Sanitizer
Active Record Session Store
Active Resource

27. Turbo Links
(aka Full Body PJAX)

30. // app/assets/javascripts/application.js
//= require jquery
//= require jquery_ujs
//= require turbolinks
//= require_tree .

34. link_to "Posts", @posts,
data: { "no-turbolinks" => true }
$(function() {
// document.ready
init();
})
$(window).bind('page.change', function() {
init();
})

35. PATCH
(aka Correct HTTP Verb)

36. GET index
GET show
GET edit
POST create
PUT update
DELETE destroy

38. Routing Concerns

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

40. concern :commentable do
resources :comments
end
concern :image_attachable do
resources :images, only: :index
end
resources :messages, concerns: :commentable
resources :posts, concerns: [:commentable, :image_attachable]

41. Rails Queue API

42. class MyJob
def run
# some expensive processing
end
end
Rails.queue.push(MyJob.new)

43. # config/application.rb
config.queue = :asynchronous
config.queue = :synchronous
# BETA
config.queue = :resque

44. Async Mailer

45. # config/application.rb
config.action_mailer.async = true

46. Active Record
(Scopes)

47. #first
ORDER BY (id) LIMIT 1
#last
ORDER BY (id) LIMIT 1
#all
doesn’t behave as an
Array
#none NullRelation

48. @users = User
@users = @users.where(id: params[:id]) if params[:id]
@users = @users.includes(:comments) if params[:comments]
@users = @users.order(:name)

49. @users = User
@users.where!(id: params[:id]) if params[:id]
@users.includes!(:comments) if params[:comments]
@users.order!(:name)

50. Post.find_by name: 'Spartacus', rating: 4
Post.find_by "published_at < ?", 2.weeks.ago
Post.find_by! name: 'Spartacus'

51. find_all_by_... where(...)
find_last_by_... where(...).last
scoped_by_... where(...)
find_or_initialize_by_... where(...).first_or_initialize
find_or_create_by_... where(...).first_or_create
find_or_create_by_...! where(...).first_or_create!

52. :conditions :where
:include :includes
:extend :extending
Post.find(:all, :conditions => {
:comments_count => 10 }, :limit => 5)
Post.where(comments_count: 10).limit(5)
Post.scoped(:where => { :comments_count => 10 },
:limit => 5)

53. scope :red, where(color: 'red')
default_scope where(color: 'red')
scope :red, -> { where(color: 'red') }
default_scope { where(color: 'red') }

54. Wrapping up

58. Thanks!
@akitaonrails