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

Transcript

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   Tricks that Rails didn’t tell you about

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   Carlos Antonio @cantoniodasilva

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   ~6 years on Rails

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   I’ve participated in several projects with different contexts

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   I’ve seen code

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   I’ve seen complex code

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   I’ve seen duplicated code

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   I’ve seen Rails code reimplemented in apps

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

   everywhere.
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    You get used to it after some time

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

    with code like that.
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    Rails tricks / features

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    That might help you refactor existing code or improve your

    developer life a bit
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    None
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    None
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    Web Development Consultancy Mainly focused in Ruby and Rails Based

    in São Paulo - Brazil
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    None
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    ❤️

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    plataformatec/devise

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    plataformatec/simple_form

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    elixir-lang/elixir

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    Rails Core Team ! Carlos Antonio

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    Rails Core Team José Valim Carlos Antonio Rafael França

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

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

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

    We’re always learning, right?
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    None
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    None
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    None
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    None
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    None
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    ಠ_ಠ I had to do this talk after this look

    of disapproval
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    Rails tricks / features Not used by many Not very

    well known and / or documented
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    What we will see: Active Record Active Model Action Mailer

    Action View Action Controller Bonus Stuff
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    Active Record

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

    -> { uniq.joins(:articles). where(articles: { status: 'draft' }) } end
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    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'
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    Relation#merge class Author < ActiveRecord::Base has_many :articles ! scope :with_draft_articles,

    -> { uniq.joins(:articles).merge(Article.draft) } end
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    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'
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    group counting >> Article.group(:status).count ! SELECT COUNT(*) AS count_all, status

    AS status FROM "articles" GROUP BY status ! => {"draft"=>7, "published"=>2}
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    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}
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    first! relation = Article.where(title: 'UNKNOWN') ! relation.first or raise(ActiveRecord::RecordNotFound, 'ZOMG

    not found') # => ZOMG Article found (ActiveRecord::RecordNotFound) ! relation.first! # => ActiveRecord::RecordNotFound
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    last! relation = Article.where(title: 'UNKNOWN') ! relation.last or raise(ActiveRecord::RecordNotFound, 'ZOMG

    not found') # => ZOMG Article found (ActiveRecord::RecordNotFound) ! relation.last! # => ActiveRecord::RecordNotFound
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    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')
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    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')
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    eager load strategies >> Article.includes(:author) ! SELECT "articles".* FROM "articles"

    ! SELECT "authors".* FROM "authors" WHERE "authors"."id" IN (980190962, 298486374)
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    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
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    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"
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    eager load strategies >> Article.preload(:author) ! SELECT "articles".* FROM “articles"

    ! SELECT "authors".* FROM “authors" WHERE "authors"."id" IN (980190962, 298486374)
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    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)
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    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
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    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
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    pluck >> Author.all.map(&:name) ! SELECT "authors".* FROM "authors" ! =>

    ["Author 2", "Author 1"]
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    pluck >> Author.select(:name).map(&:name) ! SELECT "authors"."name" FROM "authors" ! =>

    ["Author 2", "Author 1"]
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    pluck >> Author.pluck(:name) ! SELECT "authors"."name" FROM "authors" ! =>

    ["Author 2", "Author 1"]
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    pluck: multiple attrs >> Author.pluck(:name, :active) ! SELECT "authors"."name", "authors"."active"

    FROM "authors" ! => [["Author 2", true], ["Author 1", true]]
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    pluck: distinct values >> Author.distinct.pluck(:name) ! SELECT DISTINCT "authors"."name" FROM

    "authors" ! => ["Author 2", "Author 1"]
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    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"]
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    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"]
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    exists?/any? vs present? <% if @author.articles.exists? %> <%= render @author.articles

    %> <% else %> <p>No article found.</p> <% end %>
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    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]]
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    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
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    benchmark class Article < ActiveRecord::Base def self.expensive_operation sleep 2 'did

    something very expensive' end end
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    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
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    benchmark >> ActiveRecord::Base.benchmark 'SUPER EXPENSIVE OPERATION' do ?> Article.expensive_operation >>

    end SUPER EXPENSIVE OPERATION (2000.9ms) => "did something very expensive"
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    benchmark class Article < ActiveRecord::Base def self.expensive_operation benchmark 'SUPER EXPENSIVE

    OPERATION' do sleep 2 'did something very expensive' end end end
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    None
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    http://railsgirlssummerofcode.org/campaign/ And I got a free hug!

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    Active Model

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

    if name.present? && email.present? && message.present? puts 'deliver email' end end end
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    ActiveModel::Model contact = EmailContact.new contact.name = 'Carlos' contact.email = 'carlos@example.com'

    contact.message = 'ZOMG' contact.deliver
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    ActiveModel::Model <%= form_for @email_contact … %> ! <%= render @email_contact

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

    ) contact.deliver
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    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"
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    Action Mailer

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

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

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

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

    %{title}.'
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    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
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    Action View

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

    %></h2> <%= simple_format article.body %> <% end %>
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    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>
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    content_tag_for <%= content_tag_for :section, @author do |author| %> <h1><%= author.name

    %></h1> … <% end %>
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    content_tag_for <section class="author" id="author_298486374"> <h1>Author 2</h1> … </section>

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

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

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

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

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

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

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

     router to display error pages. config.exceptions_app = self.routes
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     exceptions handling # config/routes.rb ! get "/404", to: "errors#not_found" get

     "/422", to: "errors#unprocessable_entity" get "/500", to: "errors#server_error"
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     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
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     exceptions handling app/views/ errors/ not_found.html.erb server_error.html.erb unprocessable_entity.html.erb layouts/ error.html.erb

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     Bonus Time!

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     Console

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

     helper.hello_rails_conf => "Hello RailsConf 2014!" ! >> helper.class => ActionView::Base
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     application console helpers # lib/console_helpers.rb module ConsoleHelpers def a(id) Article.find(id)

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

     FROM "articles" WHERE "articles"."id" = ? LIMIT 1 [["id", 113629430]] ! => #<Article id: 113629430, …>
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     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
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     console sandbox $ rails console --sandbox … Any modifications you

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

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

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

     Hello!
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     Updating Rails

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

     …
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     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 …
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     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
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     Every single part of Rails has hidden tricks

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     They are sometimes hard to spot

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     But they can make you much more productive

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     So every time you start something new

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     Before ever considering about pattern X, Y or Z

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     Ask yourself: How Rails can help me?

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     Search API Guidelines Google Stack Overflow …

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     Ask Stack Overflow Rails Talk mailing list IRC …

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

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     And if you do find some hidden trick, remember…

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     With great moustache! ! ! ! comes great responsibility

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     Share Tweet Blog post Tell your friends …

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     Contribute Back to Rails

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     And please ping me too! ! @cantoniodasilva

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     Thank you ❤️

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     Stickers! @plataformatec

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

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

     @cantoniodasilva