Rails ガイド

$ rails generate scaffold article
      [...]
      invoke  scaffold_controller
      create    app/controllers/articles_controller.rb
      invoke    erb
      create      app/views/articles
      create      app/views/articles/index.html.erb
      create      app/views/articles/edit.html.erb
      create      app/views/articles/show.html.erb
      create      app/views/articles/new.html.erb
      create      app/views/articles/_form.html.erb
      [...]

<h1>Names of all the people</h1>
<% @people.each do |person| %>
  Name: <%= person.name %><br>
<% end %>

<%# 間違い %>
Hi, Mr. <% puts "Frodo" %>

xml.em("emphasized")
xml.em { xml.b("emph & bold") }
xml.a("A Link", "href" => "https://rubyonrails.org")
xml.target("name" => "compile", "option" => "fast")

<em>emphasized</em>
<em><b>emph &amp; bold</b></em>
<a href="https://rubyonrails.org">A link</a>
<target option="fast" name="compile" />

xml.div {
  xml.h1(@person.name)
  xml.p(@person.bio)
}

<div>
  <h1>David Heinemeier Hansson</h1>
  <p>A product of Danish Design during the Winter of '79...</p>
</div>

xml.rss("version" => "2.0", "xmlns:dc" => "http://purl.org/dc/elements/1.1/") do
  xml.channel do
    xml.title(@feed_title)
    xml.link(@url)
    xml.description "Basecamp: Recent items"
    xml.language "en-us"
    xml.ttl "40"

    for item in @recent_items
      xml.item do
        xml.title(item_title(item))
        xml.description(item_description(item)) if item_description(item)
        xml.pubDate(item_pubDate(item))
        xml.guid(@person.firm.account.url + @recent_items.url(item))
        xml.link(@person.firm.account.url + @recent_items.url(item))
        xml.tag!("dc:creator", item.author_name) if item_has_creator?(item)
      end
    end
  end
end

gem 'jbuilder'

json.name("Alex")
json.email("alex@example.com")

{
  "name": "Alex",
  "email": "alex@example.com"
}

<%= render "menu" %>

<%= render "shared/menu" %>

<%= render "shared/ad_banner" %>

<h1>Products</h1>

<p>Here are a few of our fine products:</p>
<% @products.each do |product| %>
  <%= render partial: "product", locals: {product: product} %>
<% end %>

<%= render "shared/footer" %>

<%= render partial: "product", locals: { product: @product } %>

<%= render "product", product: @product %>

<%= render partial: "product" %>

<%= render partial: "product", locals: { product: @product } %>

<%= render partial: "product", locals: { product: @item } %>

<%= render partial: "product", object: @item %>

<%= render partial: "product", object: @item, as: "item" %>

<%= render partial: "product", locals: { item: @item } %>

<% @products.each do |product| %>
  <%= render partial: "product", locals: { product: product } %>
<% end %>

<%= render partial: "product", collection: @products %>

<%= render @products %>

<%= render partial: @products, spacer_template: "product_ruler" %>

Article.create(body: 'パーシャルレイアウトはいいぞ！')

<%= render partial: 'article', layout: 'box', locals: { article: @article } %>

<div class='box'>
  <%= yield %>
</div>

<% render(layout: 'box', locals: { article: @article }) do %>
  <div>
    <p><%= article.body %></p>
  </div>
<% end %>

prepend_view_path "app/views/#{request.subdomain}"

append_view_path "app/views/direct"

config.action_controller.asset_host = "assets.example.com"
image_tag("rails.png") # => <img src="http://assets.example.com/images/rails.png" />

auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", {title: "RSS Feed"}) # =>
  <link rel="alternate" type="application/rss+xml" title="RSS Feed" href="http://www.example.com/feed" />

image_path("edit.png") # => /assets/edit.png

image_path("edit.png") # => /assets/edit-2d1a2db63fc738690021fedb5a65b68e.png

image_url("edit.png") # => http://www.example.com/assets/edit.png

image_tag("icon.png") # => <img src="/assets/icon.png" />

javascript_include_tag "common" # => <script src="/assets/common.js"></script>

javascript_path "common" # => /assets/common.js

javascript_url "common" # => http://www.example.com/assets/common.js

stylesheet_link_tag "application" # => <link href="/assets/application.css" media="screen" rel="stylesheet" />

stylesheet_path "application" # => /assets/application.css

stylesheet_url "application" # => http://www.example.com/assets/application.css

resources :articles

def index
  @articles = Article.all

  respond_to do |format|
    format.html
    format.atom
  end
end

atom_feed do |feed|
  feed.title("Articles Index")
  feed.updated(@articles.first.created_at)

  @articles.each do |article|
    feed.entry(article) do |entry|
      entry.title(article.title)
      entry.content(article.body, type: 'html')

      entry.author do |author|
        author.name(article.author_name)
      end
    end
  end
end

<% benchmark "Process data files" do %>
  <%= expensive_files_operation %>
<% end %>

<% cache do %>
  <%= render "shared/footer" %>
<% end %>

<% @greeting = capture do %>
  <p>ようこそ！日付と時刻は<%= Time.now %>です</p>
<% end %>

<html>
  <head>
    <title>ようこそ！</title>
  </head>
  <body>
    <%= @greeting %>
  </body>
</html>

<html>
  <head>
    <title>ようこそ！</title>
    <%= yield :special_script %>
  </head>
  <body>
    <p>ようこそ！日付と時刻は<%= Time.now %>です</p>
  </body>
</html>

<p>これは特別なページです。</p>

<% content_for :special_script do %>
  <script>alert('Hello!')</script>
<% end %>

date_select("article", "published_on")

datetime_select("article", "published_on")

distance_of_time_in_words(Time.now, Time.now + 15.seconds)        # => less than a minute
distance_of_time_in_words(Time.now, Time.now + 15.seconds, include_seconds: true)  # => less than 20 seconds

# 指定された日付 (ここでは本日から6日後) をデフォルト値とする日付セレクトボックスを生成する
select_date(Time.today + 6.days)

# 日付の指定がない場合、本日をデフォルト値とする日付セレクトボックスを生成する
select_date()

# 指定された日時 (ここでは本日から4日後) をデフォルト値とする日時セレクトボックスを生成する
select_datetime(Time.now + 4.days)

# 日時の指定がない場合、本日をデフォルト値とする日時セレクトボックスを生成する
select_datetime()

# 指定された日付をデフォルト値に持つセレクトボックスを生成する
select_day(Time.today + 2.days)

# 指定された数値をデフォルトの日付として持つセレクトボックスを生成する
select_day(5)

# 指定された時をデフォルト値として持つセレクトボックスを生成する
select_hour(Time.now + 6.hours)

# 指定された分をデフォルト値として持つセレクトボックスを生成する
select_minute(Time.now + 10.minutes)

# 現在の月をデフォルト値に持つセレクトボックスを生成する
select_month(Date.today)

# 指定の秒を現在時刻に加えた値をデフォルト値に持つ秒用のセレクトボックスを生成する
select_second(Time.now + 16.seconds)

# 現在時刻をデフォルト値に持つ時刻セレクトボックスを生成する
select_time(Time.now)

# 今年をデフォルト値に持ち、Date.todayで得られた日の前後5年をオプションに持つセレクトボックスを生成する
select_year(Date.today)

# 今年をデフォルト値に持ち、1900年から2009年までをオプションに持つセレクトボックスを生成する
select_year(Date.today, start_year: 1900, end_year: 2009)

time_ago_in_words(3.minutes.from_now)  # => 3分

# 時刻選択用タグを作成する。フォームがPOSTされると、submitted属性のorder変数が保存される。
time_select("order", "submitted")

my_hash = { 'first' => 1, 'second' => 'two', 'third' => [1,2,3] }
debug(my_hash)

<pre class='debug_dump'>---
first: 1
second: two
third:
- 1
- 2
- 3
</pre>

# メモ: @person変数はコントローラ側で設定済みであるとする (@person = Person.newなど)
<%= form_for @person, url: { action: "create" } do |f| %>
  <%= f.text_field :first_name %>
  <%= f.text_field :last_name %>
  <%= submit_tag 'Create' %>
<% end %>

<form action="/people/create" method="post">
  <input id="person_first_name" name="person[first_name]" type="text" />
  <input id="person_last_name" name="person[last_name]" type="text" />
  <input name="commit" type="submit" value="Create" />
</form>

{ "action" => "create", "controller" => "people", "person" => { "first_name" => "William", "last_name" => "Smith" } }

# @article.validated?が1の場合
check_box("article", "validated")
# => <input type="checkbox" id="article_validated" name="article[validated]" value="1" />
#    <input name="article[validated]" type="hidden" value="0" />

<%= form_for @person, url: { action: "update" } do |person_form| %>
  First name: <%= person_form.text_field :first_name %>
  Last name : <%= person_form.text_field :last_name %>

  <%= fields_for @person.permission do |permission_fields| %>
    Admin?  : <%= permission_fields.check_box :admin %>
  <% end %>
<% end %>

file_field(:user, :avatar)
# => <input type="file" id="user_avatar" name="user[avatar]" />

<%= form_for @article do |f| %>
  <%= f.label :title, 'Title' %>:
  <%= f.text_field :title %><br>
  <%= f.label :body, 'Body' %>:
  <%= f.text_area :body %><br>
<% end %>

hidden_field(:user, :token)
# => <input type="hidden" id="user_token" name="user[token]" value="#{@user.token}" />

label(:article, :title)
# => <label for="article_title">Title</label>

password_field(:login, :pass)
# => <input type="text" id="login_pass" name="login[pass]" value="#{@login.pass}" />

# @article.categoryが"rails"を返す場合
radio_button("article", "category", "rails")
radio_button("article", "category", "java")
# => <input type="radio" id="article_category_rails" name="article[category]" value="rails" checked="checked" />
#    <input type="radio" id="article_category_java" name="article[category]" value="java" />

text_area(:comment, :text, size: "20x30")
# => <textarea cols="20" rows="30" id="comment_text" name="comment[text]">
#      #{@comment.text}
#    </textarea>

text_field(:article, :title)
# => <input type="text" id="article_title" name="article[title]" value="#{@article.title}" />

email_field(:user, :email)
# => <input type="email" id="user_email" name="user[email]" value="#{@user.email}" />

url_field(:user, :url)
# => <input type="url" id="user_url" name="user[url]" value="#{@user.url}" />

class Article < ApplicationRecord
  belongs_to :author
end

class Author < ApplicationRecord
  has_many :articles
  def name_with_initial
    "#{first_name.first}. #{last_name}"
  end
end

collection_select(:article, :author_id, Author.all, :id, :name_with_initial, { prompt: true })

<select name="article[author_id]">
  <option value="">Please select</option>
  <option value="1" selected="selected">D. Heinemeier Hansson</option>
  <option value="2">D. Thomas</option>
  <option value="3">M. Clark</option>
</select>

class Article < ApplicationRecord
  belongs_to :author
end

class Author < AApplicationRecord
  has_many :articles
  def name_with_initial
    "#{first_name.first}. #{last_name}"
  end
end

collection_radio_buttons(:article, :author_id, Author.all, :id, :name_with_initial)

<input id="article_author_id_1" name="article[author_id]" type="radio" value="1" checked="checked" />
<label for="article_author_id_1">D. Heinemeier Hansson</label>
<input id="article_author_id_2" name="article[author_id]" type="radio" value="2" />
<label for="article_author_id_2">D. Thomas</label>
<input id="article_author_id_3" name="article[author_id]" type="radio" value="3" />
<label for="article_author_id_3">M. Clark</label>

class Article < ApplicationRecord
  has_and_belongs_to_many :authors
end

class Author < ApplicationRecord
  has_and_belongs_to_many :articles
  def name_with_initial
    "#{first_name.first}. #{last_name}"
  end
end

collection_check_boxes(:article, :author_ids, Author.all, :id, :name_with_initial)

<input id="article_author_ids_1" name="article[author_ids][]" type="checkbox" value="1" checked="checked" />
<label for="article_author_ids_1">D. Heinemeier Hansson</label>
<input id="article_author_ids_2" name="article[author_ids][]" type="checkbox" value="2" />
<label for="article_author_ids_2">D. Thomas</label>
<input id="article_author_ids_3" name="article[author_ids][]" type="checkbox" value="3" />
<label for="article_author_ids_3">M. Clark</label>
<input name="article[author_ids][]" type="hidden" value="" />

class Continent < ApplicationRecord
  has_many :countries
  # attribs: id, name
end

class Country < ApplicationRecord
  belongs_to :continent
  # attribs: id, name, continent_id
end

option_groups_from_collection_for_select(@continents, :countries, :name, :id, :name, 3)

<optgroup label="Africa">
  <option value="1">Egypt</option>
  <option value="4">Rwanda</option>
  ...
</optgroup>
<optgroup label="Asia">
  <option value="3" selected="selected">China</option>
  <option value="12">India</option>
  <option value="5">Japan</option>
  ...
</optgroup>

options_for_select([ "VISA", "MasterCard" ])
# => <option>VISA</option> <option>MasterCard</option>

options_from_collection_for_select(collection, value_method, text_method, selected = nil)

options_from_collection_for_select(@project.people, "id", "name")
# => <option value="#{person.id}">#{person.name}</option>

select("article", "person_id", Person.all.collect { |p| [ p.name, p.id ] }, { include_blank: true })

<select name="article[person_id]">
  <option value=""></option>
  <option value="1" selected="selected">David</option>
  <option value="2">Eileen</option>
  <option value="3">Rafael</option>
</select>

time_zone_select("user", "time_zone")

date_field("user", "dob")

check_box_tag 'accept'
# => <input id="accept" name="accept" type="checkbox" value="1" />

<%= field_set_tag do %>
  <p><%= text_field_tag 'name' %></p>
<% end %>
# => <fieldset><p><input id="name" name="name" type="text" /></p></fieldset>

<%= form_tag({ action: "post" }, multipart: true) do %>
  <label for="file">File to Upload</label> <%= file_field_tag "file" %>
  <%= submit_tag %>
<% end %>

file_field_tag 'attachment'
# => <input id="attachment" name="attachment" type="file" />

<%= form_tag '/articles' do %>
  <div><%= submit_tag 'Save' %></div>
<% end %>
# => <form action="/articles" method="post"><div><input type="submit" name="submit" value="Save" /></div></form>

hidden_field_tag 'token', 'VUBJKB23UIVI1UU1VOBVI@'
# => <input id="token" name="token" type="hidden" value="VUBJKB23UIVI1UU1VOBVI@" />

image_submit_tag("login.png")
# => <input src="/images/login.png" type="image" />

label_tag 'name'
# => <label for="name">Name</label>

password_field_tag 'pass'
# => <input id="pass" name="pass" type="password" />

radio_button_tag 'favorite_color', 'maroon'
# => <input id="favorite_color_maroon" name="favorite_color" type="radio" value="maroon" />

select_tag "people", "<option>David</option>"
# => <select id="people" name="people"><option>David</option></select>

submit_tag "この記事を公開"
# => <input name="commit" type="submit" value="この記事を公開" />

text_area_tag 'article'
# => <textarea id="article" name="article"></textarea>

text_field_tag 'name'
# => <input id="name" name="name" type="text" />

email_field_tag 'email'
# => <input id="email" name="email" type="email" />

url_field_tag 'url'
# => <input id="url" name="url" type="url" />

date_field_tag "dob"
# => <input id="dob" name="dob" type="date" />

button_to_function "Greeting", "alert('Hello world!')"
button_to_function "Delete", "if (confirm('Really?')) do_delete()"
button_to_function "Details" do |page|
  page[:details].visual_effect :toggle_slide
end

javascript_tag "alert('すべて良好')"

<script>
//<![CDATA[
alert('すべて良好')
//]]>
</script>

number_to_currency(1234567890.50) # => $1,234,567,890.50

number_to_human_size(1234)          # => 1.2 KB
number_to_human_size(1234567)       # => 1.2 MB

number_to_percentage(100, precision: 0)        # => 100%

number_to_phone(1235551234) # => 123-555-1234

number_with_delimiter(12345678) # => 12,345,678

number_with_precision(111.2345)                # => 111.235
number_with_precision(111.2345, precision: 2)  # => 111.23

sanitize @article.body

sanitize @article.body, tags: %w(table tr td), attributes: %w(id class style)

class Application < Rails::Application
  config.action_view.sanitized_allowed_tags = 'table', 'tr', 'td'
end

strip_links('<a href="https://rubyonrails.org">Ruby on Rails</a>')
# => Ruby on Rails

strip_links('メール送信先: <a href="mailto:me@email.com">me@email.com</a>.')
# => メール送信先: me@email.com.

strip_links('ブログ: <a href="http://myblog.com/">開く</a>')
# => ブログ: 開く

strip_tags("<i>これらの</i>タグをストリップする")
# => これらのタグをストリップする

strip_tags("<b>ボールド</b>は不要！<a href='more.html'>詳細</a>を参照")
# => ボールドは不要！詳細を参照

<%= csrf_meta_tags %>

before_action :set_expert_locale

def set_expert_locale
  I18n.locale = :expert if current_user.expert?
end