Tricks that Rails didn't tell you about @ RailsConf 2014

Transcript

1. Tricks that Rails didn’t tell you about

2. Carlos Antonio @cantoniodasilva

3. ~6 years on Rails

4. I’ve participated in several projects with different contexts

5. I’ve seen code

6. I’ve seen complex code

7. I’ve seen duplicated code

8. I’ve seen Rails code reimplemented in apps

9. How often do you see them? All the time. They're

   everywhere.

10. You get used to it after some time

11. And that’s a big problem People are afraid to deal

    with code like that.

12. Rails tricks / features

13. That might help you refactor existing code or improve your

    developer life a bit
14. None
15. None

16. Web Development Consultancy Mainly focused in Ruby and Rails Based

    in São Paulo - Brazil
17. None

18. ❤️

19. plataformatec/devise

20. plataformatec/simple_form

21. elixir-lang/elixir

22. Rails Core Team ! Carlos Antonio

23. Rails Core Team José Valim Carlos Antonio Rafael França

24. We use pull requests and code review All the f*cking

    time.

25. We do cross project code review Sometimes, when the time

    allows us.

26. And it’s usual to learn new things in the process

    We’re always learning, right?
27. None
28. None
29. None
30. None
31. None

32. ಠ_ಠ I had to do this talk after this look

    of disapproval

33. Rails tricks / features Not used by many Not very

    well known and / or documented

34. What we will see: Active Record Active Model Action Mailer

    Action View Action Controller Bonus Stuff

35. Active Record

36. migrations: change column null class ChangeNameToNotNullOnAuthors < ActiveRecord::Migration def up

    change_column :authors, :name, :string, null: false end ! def down change_column :authors, :name, :string, null: true end end

37. migrations: change column null class ChangeNameToNotNullOnAuthors < ActiveRecord::Migration def up

    change_column_null :authors, :name, false end ! def down change_column_null :authors, :name, true end end

38. migrations: change column null class ChangeNameToNotNullOnAuthors < ActiveRecord::Migration def change

    change_column :authors, :name, :string, null: false end end # => ActiveRecord::IrreversibleMigration ! class ChangeNameToNotNullOnAuthors < ActiveRecord::Migration def change change_column_null :authors, :name, false end end

39. migrations: change column default class ChangeStatusDefaultOnArticles < ActiveRecord::Migration def up

    change_column :articles, :status, :string, default: 'draft' end ! def down change_column :articles, :status, :string, default: 'published' end end

40. migrations: change column default class ChangeStatusDefaultOnArticles < ActiveRecord::Migration def up

    change_column_default :articles, :status, 'draft' end ! def down change_column_default :articles, :status, 'published' end end

41. migrations: change column default class ChangeStatusDefaultOnArticles < ActiveRecord::Migration def change

    change_column :articles, :status, :string, default: 'draft' end end # => ActiveRecord::IrreversibleMigration ! class ChangeStatusDefaultOnArticles < ActiveRecord::Migration def change change_column_default :articles, :status, 'draft' end end # => ActiveRecord::IrreversibleMigration

42. Relation#merge class Author < ActiveRecord::Base has_many :articles ! scope :with_draft_articles,

    -> { uniq.joins(:articles). where(articles: { status: 'draft' }) } end

43. Relation#merge >> Author.with_draft_articles.to_sql ! SELECT DISTINCT "authors".* FROM "authors" INNER

    JOIN "articles" ON "articles"."author_id" = "authors"."id" WHERE "articles"."status" = 'draft'

44. Relation#merge class Author < ActiveRecord::Base has_many :articles ! scope :with_draft_articles,

    -> { uniq.joins(:articles).merge(Article.draft) } end

45. Relation#merge >> Author.with_draft_articles.to_sql ! SELECT DISTINCT "authors".* FROM "authors" INNER

    JOIN "articles" ON "articles"."author_id" = "authors"."id" WHERE "articles"."status" = 'draft'

46. group counting >> Article.group(:status).count ! SELECT COUNT(*) AS count_all, status

    AS status FROM "articles" GROUP BY status ! => {"draft"=>7, "published"=>2}

47. group counting: multiple attrs >> Article.group(:status, :category).count ! SELECT COUNT(*)

    AS count_all, status AS status, category AS category FROM "articles" GROUP BY status, category ! => {["draft", nil]=>5, ["draft", "Talks"]=>2, ["published", "News"]=>1, ["published", "Releases"]=>1}

48. first! relation = Article.where(title: 'UNKNOWN') ! relation.first or raise(ActiveRecord::RecordNotFound, 'ZOMG

    not found') # => ZOMG Article found (ActiveRecord::RecordNotFound) ! relation.first! # => ActiveRecord::RecordNotFound

49. last! relation = Article.where(title: 'UNKNOWN') ! relation.last or raise(ActiveRecord::RecordNotFound, 'ZOMG

    not found') # => ZOMG Article found (ActiveRecord::RecordNotFound) ! relation.last! # => ActiveRecord::RecordNotFound

50. where.not class Article < ActiveRecord::Base scope :not_draft, -> { where

    'status != ?', 'draft' } end ! >> Article.not_draft.to_sql ! SELECT "articles".* FROM "articles" WHERE (status != 'draft')

51. where.not class Article < ActiveRecord::Base scope :not_draft, -> { where.not

    status: 'draft' } end ! >> Article.not_draft.to_sql ! SELECT "articles".* FROM "articles" WHERE ("articles"."status" != 'draft')

52. eager load strategies >> Article.includes(:author) ! SELECT "articles".* FROM "articles"

    ! SELECT "authors".* FROM "authors" WHERE "authors"."id" IN (980190962, 298486374)

53. eager load strategies >> Article.includes(:author).order('authors.name') ! SELECT "articles"."id" AS t0_r0

    ………… "authors"."updated_at" AS t1_r4 FROM "articles" LEFT OUTER JOIN "authors" ON "authors"."id" = “articles"."author_id" ORDER BY authors.name

54. eager load strategies >> Article.eager_load(:author) ! SELECT "articles"."id" AS t0_r0

    ………… "authors"."updated_at" AS t1_r4 FROM “articles" LEFT OUTER JOIN "authors" ON "authors"."id" = “articles"."author_id"

55. eager load strategies >> Article.preload(:author) ! SELECT "articles".* FROM “articles"

    ! SELECT "authors".* FROM “authors" WHERE "authors"."id" IN (980190962, 298486374)

56. eager load strategies >> Article.preload(:author).joins(:author).order('authors.name') ! SELECT "articles".* FROM "articles"

    INNER JOIN "authors" ON "authors"."id" = "articles"."author_id" ORDER BY authors.name ! SELECT "authors".* FROM "authors" WHERE "authors"."id" IN (980190962, 298486374)

57. order :asc/:desc class Article < ActiveRecord::Base scope :recent, -> {

    order 'created_at DESC' } end ! >> Article.recent ! SELECT "articles".* FROM "articles" ORDER BY created_at DESC

58. order :asc/:desc class Article < ActiveRecord::Base scope :recent, -> {

    order created_at: :desc } end ! >> Article.recent ! SELECT "articles".* FROM "articles" ORDER BY "articles"."created_at" DESC

59. pluck >> Author.all.map(&:name) ! SELECT "authors".* FROM "authors" ! =>

    ["Author 2", "Author 1"]

60. pluck >> Author.select(:name).map(&:name) ! SELECT "authors"."name" FROM "authors" ! =>

    ["Author 2", "Author 1"]

61. pluck >> Author.pluck(:name) ! SELECT "authors"."name" FROM "authors" ! =>

    ["Author 2", "Author 1"]

62. pluck: multiple attrs >> Author.pluck(:name, :active) ! SELECT "authors"."name", "authors"."active"

    FROM "authors" ! => [["Author 2", true], ["Author 1", true]]

63. pluck: distinct values >> Author.distinct.pluck(:name) ! SELECT DISTINCT "authors"."name" FROM

    "authors" ! => ["Author 2", "Author 1"]

64. to_param class Article < ActiveRecord::Base def to_param "#{id}-#{title.parameterize}" end end

    ! >> Article.all.map(&:to_param) => ["113629430-autoload", "281110143-rails-4-2-0-is-going-to-be-more-adequate", "298486374-rails-4-1-0-released", "980190962-rails-tricks"]

65. to_param class Article < ActiveRecord::Base to_param :title end ! !

    ! >> Article.all.map(&:to_param) => ["113629430-autoload", "281110143-rails-4-2-0-is", "298486374-rails-4-1-0-released", "980190962-rails-tricks"]

66. exists?/any? vs present? <% if @author.articles.exists? %> <%= render @author.articles

    %> <% else %> <p>No article found.</p> <% end %>

67. exists?/any? vs present? >> author = Author.first ! >> author.articles.exists?

    ! SELECT 1 AS one FROM "articles" WHERE "articles"."author_id" = ? LIMIT 1 [["author_id", 298486374]] ! => true ! >> author.articles.each {} ! SELECT "articles".* FROM "articles" WHERE "articles"."author_id" = ? [["author_id", 298486374]]

68. exists?/any? vs present? >> author = Author.first ! >> author.articles.present?

    ! SELECT "articles".* FROM "articles" WHERE "articles"."author_id" = ? [["author_id", 298486374]] ! => true ! >> author.articles.each {} ! # => already loaded, so no query

69. benchmark class Article < ActiveRecord::Base def self.expensive_operation sleep 2 'did

    something very expensive' end end

70. benchmark >> start = Time.now => 2014-04-21 10:48:30 -0500 >>

    Article.expensive_operation => "did something very expensive" >> finish = Time.now => 2014-04-21 10:48:32 -0500 >> finish - start => 2.02356

71. benchmark >> ActiveRecord::Base.benchmark 'SUPER EXPENSIVE OPERATION' do ?> Article.expensive_operation >>

    end SUPER EXPENSIVE OPERATION (2000.9ms) => "did something very expensive"

72. benchmark class Article < ActiveRecord::Base def self.expensive_operation benchmark 'SUPER EXPENSIVE

    OPERATION' do sleep 2 'did something very expensive' end end end
73. None

74. http://railsgirlssummerofcode.org/campaign/ And I got a free hug!

75. Active Model

76. ActiveModel::Model class EmailContact attr_accessor :name, :email, :message ! def deliver

    if name.present? && email.present? && message.present? puts 'deliver email' end end end

77. ActiveModel::Model contact = EmailContact.new contact.name = 'Carlos' contact.email = 'carlos@example.com'

    contact.message = 'ZOMG' contact.deliver

78. ActiveModel::Model <%= form_for @email_contact … %> ! <%= render @email_contact

    %>

79. ActiveModel::Model class EmailContact extend ActiveModel::Naming extend ActiveModel::Translation include ActiveModel::Validations include

    ActiveModel::Conversion ! attr_accessor :name, :email, :message validates :name, :email, :message, presence: true ! def deliver if valid? puts 'deliver email' end end ! def persisted? false end end

80. ActiveModel::Model class EmailContact include ActiveModel::Model ! attr_accessor :name, :email, :message

    validates :name, :email, :message, presence: true ! def deliver if valid? puts 'deliver email' end end end

81. ActiveModel::Model contact = EmailContact.new( name: 'Carlos', email: 'carlos@example.com', message: 'ZOMG'

    ) contact.deliver

82. ActiveModel::Model >> contact = EmailContact.new => #<EmailContact:0x007fb90e268350> ! >> contact.valid?

    => false ! >> contact.errors.full_messages.to_sentence => "Name can't be blank, Email can't be blank, and Message can't be blank"

83. Action Mailer

84. Mailer with i18n subject class Notifier < ActionMailer::Base default from:

    "from@example.com" ! # Subject can be set in your I18n file at config/locales/en.yml # with the following lookup: # # en.notifier.new_article.subject # def new_article @greeting = "Hi" ! mail to: "to@example.org" end end

85. Mailer with i18n subject class Notifier < ActionMailer::Base default from:

    "from@example.com" ! ! ! ! ! ! def new_article @greeting = "Hi" ! mail to: "to@example.org", subject: I18n.t('subjects.new_article') end end

86. Mailer with i18n subject en: subjects: new_article: 'New article just

    published.'

87. Mailer with i18n subject en: notifier: new_article: subject: 'New article

    just published.'

88. Mailer with i18n subject class Notifier < ActionMailer::Base default from:

    "from@example.com" ! def new_article @greeting = "Hi" ! mail to: "to@example.org" end end

89. Mailer with i18n subject class Notifier < ActionMailer::Base default from:

    "from@example.com" ! def new_article @greeting = "Hi" ! mail to: "to@example.org", subject: I18n.t('subjects.new_article', title: 'Clarity is king') end end

90. Mailer with i18n subject en: subjects: new_article: 'New article: %{title}.'

91. Mailer with i18n subject en: notifier: new_article: subject: 'New article

    %{title}.'

92. Mailer with i18n subject class Notifier < ActionMailer::Base default from:

    "from@example.com" ! def new_article @greeting = "Hi" ! mail to: "to@example.org", subject: default_i18n_subject(title: 'Clarity is king') end end

93. Action View

94. content_tag_for <%= content_tag_for :article, @articles do |article| %> <h2><%= article.title

    %></h2> <%= simple_format article.body %> <% end %>

95. content_tag_for <article class="article" id="article_281110143"> <h2>Rails 4.2.0 is going to be

    more Adequate</h2> <p>Rails 4.2.0 is going to be made more Adequate by Tenderlove and Gorby Puff</p> </article> <article class="article" id="article_298486374"> <h2>Rails 4.1.0 Released</h2> <p>Rails 4.1.0 was just released before RailsConf</p> </article>

96. content_tag_for <%= content_tag_for :section, @author do |author| %> <h1><%= author.name

    %></h1> … <% end %>

97. content_tag_for <section class="author" id="author_298486374"> <h1>Author 2</h1> … </section>

98. render empty collections <% if author.articles.exists? %> <%= render author.articles

    %> <% else %> <p>No article found.</p> <% end %>

99. render empty collections <%= render(author.articles) || content_tag(:p, 'No article found.')

    %>

100. partial locals <%= render article, full: true %> <%= render

     author.articles, full: false %> ! # article partial <%= content_tag_for :article, article do |article| %> <h2><%= article.title %></h2> ! <% if full %> <%= simple_format article.body %> <% else %> <%= truncate article.body %> <% end %> <% end %>

101. partial locals <%= render article, full: true %> <%= render

     author.articles %> ! # article partial <%= content_tag_for :article, article do |article| %> <h2><%= article.title %></h2> ! <% if local_assigns[:full] %> <%= simple_format article.body %> <% else %> <%= truncate article.body %> <% end %> <% end %>

102. truncate text <%= truncate article.body do %> <%= link_to 'read

     more...', article %> <% end %> ! ! Rails 4.2.0 is going to be ... <a href="/articles/281110143-rails-4-2-0-is"> read more… </a>

103. I18n + html <%= link_to I18n.t('read_more'), article %> ! !

     en: read_more: 'read more…' ! ! <a href="/articles/281110143-rails-4-2-0-is"> read more… </a>

104. I18n + html <%= link_to I18n.t('read_more'), article %> ! !

     en: read_more: 'read <b>more</b>…' ! ! <a href="/articles/281110143-rails-4-2-0-is"> read &lt;b&gt;more&lt;/b&gt;… </a>

105. I18n + html <%= link_to raw(I18n.t('read_more')), article %> ! !

     en: read_more: 'read <b>more</b>…' ! ! <a href="/articles/281110143-rails-4-2-0-is"> read <b>more</b>… </a>

106. I18n + html <%= link_to I18n.t(‘read_more_html'), article %> ! !

     en: read_more_html: 'read <b>more</b>…' ! ! <a href="/articles/281110143-rails-4-2-0-is"> read <b>more</b>… </a>

107. benchmark <% benchmark 'Rendering articles' do %> <%= sleep(2); render

     author.articles %> <% end %> ! ! # logger Rendering articles (2005.1ms)

108. Action Controller

109. redirects with params get '/articles/:id' => redirect('/articles/%{id}/edit')

110. exceptions handling $ ls public/*.html ! 404.html 422.html 500.html

111. exceptions handling # config/application.rb ! # Use the app's own

     router to display error pages. config.exceptions_app = self.routes

112. exceptions handling # config/routes.rb ! get "/404", to: "errors#not_found" get

     "/422", to: "errors#unprocessable_entity" get "/500", to: "errors#server_error"

113. exceptions handling class ErrorsController < ApplicationController layout "error" ! def

     not_found render status: :not_found end ! def server_error render status: :server_error end ! def unprocessable_entity render status: :unprocessable_entity end end

114. exceptions handling app/views/ errors/ not_found.html.erb server_error.html.erb unprocessable_entity.html.erb layouts/ error.html.erb

115. Bonus Time!

116. Console

117. app >> app.author_path(Author.first) => “/authors/298486374" ! >> app.get _ Started

     GET "/authors/298486374" for 127.0.0.1 at 2014-04-22 19:31:04 -0500 Processing by AuthorsController#show as HTML … Rendered authors/show.html.erb within layouts/application (1.1ms) Completed 200 OK in 9ms (Views: 7.7ms | ActiveRecord: 0.2ms) => 200 ! >> app.class => ActionDispatch::Integration::Session

118. helper >> helper.time_ago_in_words 30.days.ago => "about 1 month" ! >>

     helper.hello_rails_conf => "Hello RailsConf 2014!" ! >> helper.class => ActionView::Base

119. application console helpers # lib/console_helpers.rb module ConsoleHelpers def a(id) Article.find(id)

     end end

120. application console helpers # config/application.rb module RailsConf2014 class Application <

     Rails::Application console do require 'console_helpers' Rails::ConsoleMethods.send :include, ConsoleHelpers end end end

121. application console helpers >> a(113629430) Article Load (0.1ms) SELECT "articles".*

     FROM "articles" WHERE "articles"."id" = ? LIMIT 1 [["id", 113629430]] ! => #<Article id: 113629430, …>

122. console sandbox $ rails console >> Article.count => 4 !

     $ rails console --sandbox >> Article.create! title: 'I will be rolled back' => #<Article id: 980190968, title: "I will be rolled back", …> >> Article.count => 5 ! $ rails console >> Article.count => 4

123. console sandbox $ rails console --sandbox … Any modifications you

     make will be rolled back on exit ! ! ! >> exit rollback transaction

124. Annotations

125. annotations class Author < ActiveRecord::Base # TODO: create inactive scope

     scope :active, -> { where active: true } end ! class Article < ActiveRecord::Base # FIXME: Fix for RailsConf scope :published, -> { where status: 'published' } end ! class AuthorsController < ApplicationController # OPTIMIZE: eager load stuff def show @author = Author.find(params[:id]) end end

126. annotations $ rake notes ! app/controllers/authors_controller.rb: * [2] [OPTIMIZE] eager

     load stuff ! app/models/article.rb: * [9] [FIXME] Fix for RailsConf ! app/models/author.rb: * [4] [TODO] create inactive scope

127. custom annotations class Notifier < ActionMailer::Base # RAILSCONF: Hello! def

     new_article end end

128. custom annotations $ rake notes:custom ANNOTATION=RAILSCONF ! app/mailers/notifier.rb: * [4]

     Hello!

129. Updating Rails

130. rails update gem 'rails', '4.1.0' ! ! $ bundle update

     …

131. rails update $ rake rails:update identical config/boot.rb exist config conflict

     config/routes.rb ./railsconf2014-404/config/routes.rb? (enter "h" for help) [Ynaqdh] h Y - yes, overwrite n - no, do not overwrite a - all, overwrite this and all others q - quit, abort d - diff, show the differences between the old and the new h - help, show this help ./railsconf2014-404/config/routes.rb? (enter "h" for help) [Ynaqdh] a force config/routes.rb … exist config/initializers identical config/initializers/backtrace_silencers.rb create config/initializers/cookies_serializer.rb identical config/initializers/filter_parameter_logging.rb …

132. rails update $ git status On branch master Changes not

     staged for commit: (use "git add <file>..." to update what will be committed) (use "git checkout -- <file>..." to discard changes in working directory) ! modified: Gemfile modified: Gemfile.lock modified: config/environment.rb modified: config/environments/development.rb modified: config/environments/production.rb modified: config/environments/test.rb modified: config/initializers/mime_types.rb modified: config/initializers/session_store.rb modified: config/routes.rb ! Untracked files: (use "git add <file>..." to include in what will be committed) ! config/initializers/cookies_serializer.rb config/secrets.yml

133. Every single part of Rails has hidden tricks

134. They are sometimes hard to spot

135. But they can make you much more productive

136. So every time you start something new

137. Before ever considering about pattern X, Y or Z

138. Ask yourself: How Rails can help me?

139. Search API Guidelines Google Stack Overflow …

140. Ask Stack Overflow Rails Talk mailing list IRC …

141. Follow Changelogs Release Notes Upgrading Guides Commits (if you can)

142. And if you do find some hidden trick, remember…

143. With great moustache! ! ! ! comes great responsibility

144. Share Tweet Blog post Tell your friends …

145. Contribute Back to Rails

146. And please ping me too! ! @cantoniodasilva

147. Thank you ❤️

148. Stickers! @plataformatec

149. Questions? Get one of these mugs (5 only :D)

150. Tricks that Rails! didn’t tell you about Carlos Antonio -

     @cantoniodasilva