Action Viewフォームヘルパー

<%= form_with do |form| %>
  フォームの内容
<% end %>

<form accept-charset="UTF-8" action="/" method="post">
  <input name="authenticity_token" type="hidden" value="J7CBxfHalt49OSHp27hblqK20c9PgwJ108nDHX/8Cts=" />
  フォームの内容
</form>

<%= form_with url: "/search", method: :get do |form| %>
  <%= form.label :query, "Search for:" %>
  <%= form.text_field :query %>
  <%= form.submit "Search" %>
<% end %>

<form action="/search" method="get" accept-charset="UTF-8" >
  <label for="query">Search for:</label>
  <input id="query" name="query" type="text" />
  <input name="commit" type="submit" value="Search" data-disable-with="Search" />
</form>

<%= form.check_box :pet_dog %>
<%= form.label :pet_dog, "I own a dog" %>
<%= form.check_box :pet_cat %>
<%= form.label :pet_cat, "I own a cat" %>

<input type="checkbox" id="pet_dog" name="pet_dog" value="1" />
<label for="pet_dog">I own a dog</label>
<input type="checkbox" id="pet_cat" name="pet_cat" value="1" />
<label for="pet_cat">I own a cat</label>

<%= form.radio_button :age, "child" %>
<%= form.label :age_child, "I am younger than 21" %>
<%= form.radio_button :age, "adult" %>
<%= form.label :age_adult, "I am over 21" %>

<input type="radio" id="age_child" name="age" value="child" />
<label for="age_child">I am younger than 21</label>
<input type="radio" id="age_adult" name="age" value="adult" />
<label for="age_adult">I am over 21</label>

<%= form.text_area :message, size: "70x5" %>
<%= form.hidden_field :parent_id, value: "foo" %>
<%= form.password_field :password %>
<%= form.number_field :price, in: 1.0..20.0, step: 0.5 %>
<%= form.range_field :discount, in: 1..100 %>
<%= form.date_field :born_on %>
<%= form.time_field :started_at %>
<%= form.datetime_local_field :graduation_day %>
<%= form.month_field :birthday_month %>
<%= form.week_field :birthday_week %>
<%= form.search_field :name %>
<%= form.email_field :address %>
<%= form.telephone_field :phone %>
<%= form.url_field :homepage %>
<%= form.color_field :favorite_color %>

<textarea name="message" id="message" cols="70" rows="5"></textarea>
<input type="hidden" name="parent_id" id="parent_id" value="foo" />
<input type="password" name="password" id="password" />
<input type="number" name="price" id="price" step="0.5" min="1.0" max="20.0" />
<input type="range" name="discount" id="discount" min="1" max="100" />
<input type="date" name="born_on" id="born_on" />
<input type="time" name="started_at" id="started_at" />
<input type="datetime-local" name="graduation_day" id="graduation_day" />
<input type="month" name="birthday_month" id="birthday_month" />
<input type="week" name="birthday_week" id="birthday_week" />
<input type="search" name="name" id="name" />
<input type="email" name="address" id="address" />
<input type="tel" name="phone" id="phone" />
<input type="url" name="homepage" id="homepage" />
<input type="color" name="favorite_color" id="favorite_color" value="#000000" />

@article = Article.find(42)
# => #<Article id: 42, title: "My Title", body: "My Body">

<%= form_with model: @article do |form| %>
  <%= form.text_field :title %>
  <%= form.text_area :body, size: "60x10" %>
  <%= form.submit %>
<% end %>

<form action="/articles/42" method="post" accept-charset="UTF-8" >
  <input name="authenticity_token" type="hidden" value="..." />
  <input type="text" name="article[title]" id="article_title" value="My Title" />
  <textarea name="article[body]" id="article_body" cols="60" rows="10">
    My Body
  </textarea>
  <input type="submit" name="commit" value="Update Article" data-disable-with="Update Article">
</form>

<%= form_with model: @person do |person_form| %>
  <%= person_form.text_field :name %>
  <%= fields_for :contact_detail, @person.contact_detail do |contact_detail_form| %>
    <%= contact_detail_form.text_field :phone_number %>
  <% end %>
<% end %>

<form action="/people" accept-charset="UTF-8" method="post">
  <input type="hidden" name="authenticity_token" value="bL13x72pldyDD8bgtkjKQakJCpd4A8JdXGbfksxBDHdf1uC0kCMqe2tvVdUYfidJt0fj3ihC4NxiVHv8GVYxJA==" />
  <input type="text" name="person[name]" id="person_name" />
  <input type="text" name="contact_detail[phone_number]" id="contact_detail_phone_number" />
</form>

resources :articles

## 新しい記事を作成する
# 長いスタイル：
form_with(model: @article, url: articles_path)
# 短いスタイル：
form_with(model: @article)

## 既存の記事を編集する
# 長いスタイル：
form_with(model: @article, url: article_path(@article), method: "patch")
# 短いスタイル：
form_with(model: @article)

resource :geocoder
resolve('Geocoder') { [:geocoder] }

form_with model: [:admin, @article]

form_with model: [:admin, :management, @article]

form_with(url: search_path, method: "patch")

<form accept-charset="UTF-8" action="/search" method="post">
  <input name="_method" type="hidden" value="patch" />
  <input name="authenticity_token" type="hidden" value="f755bb0ed134b76c432144748a6d4b7a7ddf2b71" />
  <!-- ... -->
</form>

<%= form_with url: "/posts/1", method: :patch do |form| %>
  <%= form.button "Delete", formmethod: :delete, data: { confirm: "Are you sure?" } %>
  <%= form.button "Update" %>
<% end %>

<form accept-charset="UTF-8" action="/posts/1" method="post">
  <input name="_method" type="hidden" value="patch" />
  <input name="authenticity_token" type="hidden" value="f755bb0ed134b76c432144748a6d4b7a7ddf2b71" />
  <!-- ... -->

  <button type="submit" formmethod="post" name="_method" value="delete" data-confirm="Are you sure?">Delete</button>
  <button type="submit" name="button">Update</button>
</form>

<%= form.select :city, ["Berlin", "Chicago", "Madrid"] %>

<select name="city" id="city">
  <option value="Berlin">Berlin</option>
  <option value="Chicago">Chicago</option>
  <option value="Madrid">Madrid</option>
</select>

<%= form.select :city, [["Berlin", "BE"], ["Chicago", "CHI"], ["Madrid", "MD"]] %>

<select name="city" id="city">
  <option value="BE">Berlin</option>
  <option value="CHI">Chicago</option>
  <option value="MD">Madrid</option>
</select>

<%= form.select :city, [["Berlin", "BE"], ["Chicago", "CHI"], ["Madrid", "MD"]], selected: "CHI" %>

<select name="city" id="city">
  <option value="BE">Berlin</option>
  <option value="CHI" selected="selected">Chicago</option>
  <option value="MD">Madrid</option>
</select>

<select name="city" id="city">
  <optgroup label="ヨーロッパ">
    <option value="BE">ベルリン</option>
    <option value="MD">マドリード</option>
  </optgroup>
  <optgroup label="北アメリカ">
    <option value="CHI" selected="selected">シカゴ</option>
  </optgroup>
</select>

@person = Person.new(city: "MD")

<%= form_with model: @person do |form| %>
  <%= form.select :city, [["ベルリン", "BE"], ["シカゴ", "CHI"], ["マドリード", "MD"]] %>
<% end %>

<select name="person[city]" id="person_city">
  <option value="BE">ベルリン</option>
  <option value="CHI">シカゴ</option>
  <option value="MD" selected="selected">マドリード</option>
</select>

<%= form.time_zone_select :time_zone %>

@person = Person.new(birth_date: Date.new(1995, 12, 21))

<%= form_with model: @person do |form| %>
  <%= form.date_select :birth_date %>
<% end %>

<select name="person[birth_date(1i)]" id="person_birth_date_1i">
  <option value="1990">1990</option>
  <option value="1991">1991</option>
  <option value="1992">1992</option>
  <option value="1993">1993</option>
  <option value="1994">1994</option>
  <option value="1995" selected="selected">1995</option>
  <option value="1996">1996</option>
  <option value="1997">1997</option>
  <option value="1998">1998</option>
  <option value="1999">1999</option>
  <option value="2000">2000</option>
</select>
<select name="person[birth_date(2i)]" id="person_birth_date_2i">
  <option value="1">1月</option>
  <option value="2">2月</option>
  <option value="3">3月</option>
  <option value="4">4月</option>
  <option value="5">5月</option>
  <option value="6">6月</option>
  <option value="7">7月</option>
  <option value="8">8月</option>
  <option value="9">9月</option>
  <option value="10">10月</option>
  <option value="11">11月</option>
  <option value="12" selected="selected">12月</option>
</select>
<select name="person[birth_date(3i)]" id="person_birth_date_3i">
  <option value="1">1</option>
  ...
  <option value="21" selected="selected">21</option>
  ...
  <option value="31">31</option>
</select>

<%= select_year 1999, prefix: "party" %>

<select name="party[year]" id="party_year">
  <option value="1994">1994</option>
  <option value="1995">1995</option>
  <option value="1996">1996</option>
  <option value="1997">1997</option>
  <option value="1998">1998</option>
  <option value="1999" selected="selected">1999</option>
  <option value="2000">2000</option>
  <option value="2001">2001</option>
  <option value="2002">2002</option>
  <option value="2003">2003</option>
  <option value="2004">2004</option>
</select>

class City < ApplicationRecord
end

class Person < ApplicationRecord
  belongs_to :city
end

City.order(:name).map { |city| [city.name, city.id] }
# => [["Berlin", 3], ["Chicago", 1], ["Madrid", 2]]

<%= form_with model: @person do |form| %>
  <%= form.select :city_id, City.order(:name).map { |city| [city.name, city.id] } %>
<% end %>

<%= form.collection_select :city_id, City.order(:name), :id, :name %>

<select name="person[city_id]" id="person_city_id">
  <option value="3">Berlin</option>
  <option value="1">Chicago</option>
  <option value="2">Madrid</option>
</select>

<%= form.collection_radio_buttons :city_id, City.order(:name), :id, :name %>

<input type="radio" name="person[city_id]" value="3" id="person_city_id_3">
<label for="person_city_id_3">Berlin</label>

<input type="radio" name="person[city_id]" value="1" id="person_city_id_1">
<label for="person_city_id_1">Chicago</label>

<input type="radio" name="person[city_id]" value="2" id="person_city_id_2">
<label for="person_city_id_2">Madrid</label>

<%= form.collection_check_boxes :interest_ids, Interest.order(:name), :id, :name %>

<input type="checkbox" name="person[interest_id][]" value="3" id="person_interest_id_3">
<label for="person_interest_id_3">Engineering</label>

<input type="checkbox" name="person[interest_id][]" value="4" id="person_interest_id_4">
<label for="person_interest_id_4">Math</label>

<input type="checkbox" name="person[interest_id][]" value="1" id="person_interest_id_1">
<label for="person_interest_id_1">Science</label>

<input type="checkbox" name="person[interest_id][]" value="2" id="person_interest_id_2">
<label for="person_interest_id_2">Technology</label>

<%= form_with model: @person do |form| %>
  <%= form.file_field :picture %>
<% end %>

<%= form_with url: "/uploads", multipart: true do |form| %>
  <%= file_field_tag :picture %>
<% end %>

def upload
  uploaded_file = params[:picture]
  File.open(Rails.root.join('public', 'uploads', uploaded_file.original_filename), 'wb') do |file|
    file.write(uploaded_file.read)
  end
end

<%= form_with model: @person do |form| %>
  <%= text_field_with_label form, :first_name %>
<% end %>

<%= form_with model: @person, builder: LabellingFormBuilder do |form| %>
  <%= form.text_field :first_name %>
<% end %>

class LabellingFormBuilder < ActionView::Helpers::FormBuilder
  def text_field(attribute, options = {})
    label(attribute) + super
  end
end

def labeled_form_with(model: nil, scope: nil, url: nil, format: nil, **options, &block)
  options[:builder] = LabellingFormBuilder
  form_with model: model, scope: scope, url: url, format: format, **options, &block
end

<%= render partial: f %>

<input id="person_name" name="person[name]" type="text" value="Henry"/>

{ 'person' => { 'name' => 'Henry' } }

<input id="person_address_city" name="person[address][city]" type="text" value="New York"/>

{ 'person' => { 'address' => { 'city' => 'New York' } } }

<input name="person[phone_number][]" type="text"/>
<input name="person[phone_number][]" type="text"/>
<input name="person[phone_number][]" type="text"/>

<input name="person[addresses][][line1]" type="text"/>
<input name="person[addresses][][line2]" type="text"/>
<input name="person[addresses][][city]" type="text"/>
<input name="person[addresses][][line1]" type="text"/>
<input name="person[addresses][][line2]" type="text"/>
<input name="person[addresses][][city]" type="text"/>

<%= form_with model: @person do |person_form| %>
  <%= person_form.text_field :name %>
  <% @person.addresses.each do |address| %>
    <%= person_form.fields_for address, index: address.id do |address_form| %>
      <%= address_form.text_field :city %>
    <% end %>
  <% end %>
<% end %>

<form accept-charset="UTF-8" action="/people/1" method="post">
  <input name="_method" type="hidden" value="patch" />
  <input id="person_name" name="person[name]" type="text" />
  <input id="person_address_23_city" name="person[address][23][city]" type="text" />
  <input id="person_address_45_city" name="person[address][45][city]" type="text" />
</form>

{
  "person" => {
    "name" => "Bob",
    "address" => {
      "23" => {
        "city" => "Paris"
      },
      "45" => {
        "city" => "London"
      }
    }
  }
}

<%= fields_for 'person[address][primary]', address, index: address.id do |address_form| %>
  <%= address_form.text_field :city %>
<% end %>

<input id="person_address_primary_23_city" name="person[address][primary][23][city]" type="text" value="Paris" />

<%= fields_for 'person[address][primary][]', address do |address_form| %>
  <%= address_form.text_field :city %>
<% end %>

<%= form_with url: 'http://farfar.away/form', authenticity_token: 'external_token' do %>
  フォームの内容
<% end %>

<%= form_with url: 'http://farfar.away/form', authenticity_token: false do %>
  フォームの内容
<% end %>

class Person < ApplicationRecord
  has_many :addresses, inverse_of: :person
  accepts_nested_attributes_for :addresses
end

class Address < ApplicationRecord
  belongs_to :person
end

<%= form_with model: @person do |form| %>
  Addresses:
  <ul>
    <%= form.fields_for :addresses do |addresses_form| %>
      <li>
        <%= addresses_form.label :kind %>
        <%= addresses_form.text_field :kind %>

        <%= addresses_form.label :street %>
        <%= addresses_form.text_field :street %>
        ...
      </li>
    <% end %>
  </ul>
<% end %>

def new
  @person = Person.new
  2.times { @person.addresses.build }
end

{
  'person' => {
    'name' => 'John Doe',
    'addresses_attributes' => {
      '0' => {
        'kind' => 'Home',
        'street' => '221b Baker Street'
      },
      '1' => {
        'kind' => 'Office',
        'street' => '31 Spooner Street'
      }
    }
  }
}

def create
  @person = Person.new(person_params)
  # ...
end

private
  def person_params
    params.require(:person).permit(:name, addresses_attributes: [:id, :kind, :street])
  end

class Person < ApplicationRecord
  has_many :addresses
  accepts_nested_attributes_for :addresses, allow_destroy: true
end

<%= form_with model: @person do |form| %>
  Addresses:
  <ul>
    <%= form.fields_for :addresses do |addresses_form| %>
      <li>
        <%= addresses_form.check_box :_destroy %>
        <%= addresses_form.label :kind %>
        <%= addresses_form.text_field :kind %>
        ...
      </li>
    <% end %>
  </ul>
<% end %>

def person_params
  params.require(:person).
    permit(:name, addresses_attributes: [:id, :kind, :street, :_destroy])
end

<%= check_box_tag "accept" %>

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