module ActionView::Helpers::UrlHelper

# File actionview/lib/action_view/helpers/url_helper.rb, line 294
def button_to(name = nil, options = nil, html_options = nil, &block)
  html_options, options = options, name if block_given?
  options      ||= {}
  html_options ||= {}
  html_options = html_options.stringify_keys

  url    = options.is_a?(String) ? options : url_for(options)
  remote = html_options.delete('remote')
  params = html_options.delete('params')

  method     = html_options.delete('method').to_s
  method_tag = BUTTON_TAG_METHOD_VERBS.include?(method) ? method_tag(method) : ''.freeze.html_safe

  form_method  = method == 'get' ? 'get' : 'post'
  form_options = html_options.delete('form') || {}
  form_options[:class] ||= html_options.delete('form_class') || 'button_to'
  form_options[:method] = form_method
  form_options[:action] = url
  form_options[:'data-remote'] = true if remote

  request_token_tag = if form_method == 'post'
    request_method = method.empty? ? 'post' : method
    token_tag(nil, form_options: { action: url, method: request_method })
  else
    ''.freeze
  end

  html_options = convert_options_to_data_attributes(options, html_options)
  html_options['type'] = 'submit'

  button = if block_given?
    content_tag('button', html_options, &block)
  else
    html_options['value'] = name || url
    tag('input', html_options)
  end

  inner_tags = method_tag.safe_concat(button).safe_concat(request_token_tag)
  if params
    to_form_params(params).each do |param|
      inner_tags.safe_concat tag(:input, type: "hidden", name: param[:name], value: param[:value])
    end
  end
  content_tag('form', inner_tags, form_options)
end

Generates a form containing a single button that submits to the URL created by the set of options. This is the safest method to ensure links that cause changes to your data are not triggered by search bots or accelerators. If the HTML button does not work with your layout, you can also consider using the link_to method with the :method modifier as described in the link_to documentation.

By default, the generated form element has a class name of button_to to allow styling of the form itself and its children. This can be changed using the :form_class modifier within html_options. You can control the form submission and input element behavior using html_options. This method accepts the :method modifier described in the link_to documentation. If no :method modifier is given, it will default to performing a POST operation. You can also disable the button by passing disabled: true in html_options. If you are using RESTful routes, you can pass the :method to change the HTTP verb used to submit the form.

Options

The options hash accepts the same options as url_for.

There are a few special html_options:

• :method - Symbol of HTTP verb. Supported verbs are :post, :get, :delete, :patch, and :put. By default it will be :post.

• :disabled - If set to true, it will generate a disabled button.

• :data - This option can be used to add custom data attributes.

• :remote - If set to true, will allow the Unobtrusive JavaScript drivers to control the submit behavior. By default this behavior is an ajax submit.

• :form - This hash will be form attributes

• :form_class - This controls the class of the form within which the submit button will be placed

• :params - Hash of parameters to be rendered as hidden fields within the form.

Data attributes

• :confirm - This will use the unobtrusive JavaScript driver to prompt with the question specified. If the user accepts, the link is processed normally, otherwise no action is taken.

• :disable_with - Value of this parameter will be used as the value for a disabled version of the submit button when the form is submitted. This feature is provided by the unobtrusive JavaScript driver.

Examples

<%= button_to "New", action: "new" %>
# => "<form method="post" action="/controller/new" class="button_to">
#      <input value="New" type="submit" />
#    </form>"

<%= button_to "New", new_articles_path %>
# => "<form method="post" action="/articles/new" class="button_to">
#      <input value="New" type="submit" />
#    </form>"

<%= button_to [:make_happy, @user] do %>
  Make happy <strong><%= @user.name %></strong>
<% end %>
# => "<form method="post" action="/users/1/make_happy" class="button_to">
#      <button type="submit">
#        Make happy <strong><%= @user.name %></strong>
#      </button>
#    </form>"

<%= button_to "New", { action: "new" }, form_class: "new-thing" %>
# => "<form method="post" action="/controller/new" class="new-thing">
#      <input value="New" type="submit" />
#    </form>"

<%= button_to "Create", { action: "create" }, remote: true, form: { "data-type" => "json" } %>
# => "<form method="post" action="/images/create" class="button_to" data-remote="true" data-type="json">
#      <input value="Create" type="submit" />
#      <input name="authenticity_token" type="hidden" value="10f2163b45388899ad4d5ae948988266befcb6c3d1b2451cf657a0c293d605a6"/>
#    </form>"

<%= button_to "Delete Image", { action: "delete", id: @image.id },
                                method: :delete, data: { confirm: "Are you sure?" } %>
# => "<form method="post" action="/images/delete/1" class="button_to">
#      <input type="hidden" name="_method" value="delete" />
#      <input data-confirm='Are you sure?' value="Delete Image" type="submit" />
#      <input name="authenticity_token" type="hidden" value="10f2163b45388899ad4d5ae948988266befcb6c3d1b2451cf657a0c293d605a6"/>
#    </form>"

<%= button_to('Destroy', 'http://www.example.com',
          method: "delete", remote: true, data: { confirm: 'Are you sure?', disable_with: 'loading...' }) %>
# => "<form class='button_to' method='post' action='http://www.example.com' data-remote='true'>
#       <input name='_method' value='delete' type='hidden' />
#       <input value='Destroy' type='submit' data-disable-with='loading...' data-confirm='Are you sure?' />
#       <input name="authenticity_token" type="hidden" value="10f2163b45388899ad4d5ae948988266befcb6c3d1b2451cf657a0c293d605a6"/>
#     </form>"
#

# File actionview/lib/action_view/helpers/url_helper.rb, line 534
def current_page?(options)
  unless request
    raise "You cannot use helpers that need to determine the current "                  "page unless your view context provides a Request object "                  "in a #request method"
  end

  return false unless request.get? || request.head?

  url_string = URI.parser.unescape(url_for(options)).force_encoding(Encoding::BINARY)

  # We ignore any extra parameters in the request_uri if the
  # submitted url doesn't have any either. This lets the function
  # work with things like ?order=asc
  request_uri = url_string.index("?") ? request.fullpath : request.path
  request_uri = URI.parser.unescape(request_uri).force_encoding(Encoding::BINARY)

  url_string.chomp!("/") if url_string.start_with?("/") && url_string != "/"

  if url_string =~ /^\w+:\/\//
    url_string == "#{request.protocol}#{request.host_with_port}#{request_uri}"
  else
    url_string == request_uri
  end
end

True if the current request URI was generated by the given options.

Examples

Let's say we're in the http://www.example.com/shop/checkout?order=desc&page=1 action.

current_page?(action: 'process')
# => false

current_page?(action: 'checkout')
# => true

current_page?(controller: 'library', action: 'checkout')
# => false

current_page?(controller: 'shop', action: 'checkout')
# => true

current_page?(controller: 'shop', action: 'checkout', order: 'asc')
# => false

current_page?(controller: 'shop', action: 'checkout', order: 'desc', page: '1')
# => true

current_page?(controller: 'shop', action: 'checkout', order: 'desc', page: '2')
# => false

current_page?('http://www.example.com/shop/checkout')
# => true

current_page?('/shop/checkout')
# => true

current_page?('http://www.example.com/shop/checkout?order=desc&page=1')
# => true

Let's say we're in the http://www.example.com/products action with method POST in case of invalid product.

current_page?(controller: 'product', action: 'index')
# => false

We can also pass in the symbol arguments instead of strings.

# File actionview/lib/action_view/helpers/url_helper.rb, line 190
def link_to(name = nil, options = nil, html_options = nil, &block)
  html_options, options, name = options, name, block if block_given?
  options ||= {}

  html_options = convert_options_to_data_attributes(options, html_options)

  url = url_for(options)
  html_options["href".freeze] ||= url

  content_tag("a".freeze, name || url, html_options, &block)
end

Creates an anchor element of the given name using a URL created by the set of options. See the valid options in the documentation for url_for. It's also possible to pass a String instead of an options hash, which generates an anchor element that uses the value of the String as the href for the link. Using a :back Symbol instead of an options hash will generate a link to the referrer (a JavaScript back link will be used in place of a referrer if none exists). If nil is passed as the name the value of the link itself will become the name.

Signatures

link_to(body, url, html_options = {})
  # url is a String; you can use URL helpers like
  # posts_path

link_to(body, url_options = {}, html_options = {})
  # url_options, except :method, is passed to url_for

link_to(options = {}, html_options = {}) do
  # name
end

link_to(url, html_options = {}) do
  # name
end

Options

• :data - This option can be used to add custom data attributes.

• method: symbol of HTTP verb - This modifier will dynamically create an HTML form and immediately submit the form for processing using the HTTP verb specified. Useful for having links perform a POST operation in dangerous actions like deleting a record (which search bots can follow while spidering your site). Supported verbs are :post, :delete, :patch, and :put. Note that if the user has JavaScript disabled, the request will fall back to using GET. If href: '#' is used and the user has JavaScript disabled clicking the link will have no effect. If you are relying on the POST behavior, you should check for it in your controller's action by using the request object's methods for post?, delete?, patch?, or put?.

• remote: true - This will allow the unobtrusive JavaScript driver to make an Ajax request to the URL in question instead of following the link. The drivers each provide mechanisms for listening for the completion of the Ajax request and performing JavaScript operations once they're complete

Data attributes

• confirm: 'question?' - This will allow the unobtrusive JavaScript driver to prompt with the question specified (in this case, the resulting text would be question?. If the user accepts, the link is processed normally, otherwise no action is taken.

• :disable_with - Value of this parameter will be used as the value for a disabled version of the submit button when the form is submitted. This feature is provided by the unobtrusive JavaScript driver.

Examples

Because it relies on url_for, link_to supports both older-style controller/action/id arguments and newer RESTful routes. Current Rails style favors RESTful routes whenever possible, so base your application on resources and use

link_to "Profile", profile_path(@profile)
# => <a href="/profiles/1">Profile</a>

or the even pithier

link_to "Profile", @profile
# => <a href="/profiles/1">Profile</a>

in place of the older more verbose, non-resource-oriented

link_to "Profile", controller: "profiles", action: "show", id: @profile
# => <a href="/profiles/show/1">Profile</a>

Similarly,

link_to "Profiles", profiles_path
# => <a href="/profiles">Profiles</a>

is better than

link_to "Profiles", controller: "profiles"
# => <a href="/profiles">Profiles</a>

You can use a block as well if your link target is hard to fit into the name parameter. ERB example:

<%= link_to(@profile) do %>
  <strong><%= @profile.name %></strong> -- <span>Check it out!</span>
<% end %>
# => <a href="/profiles/1">
       <strong>David</strong> -- <span>Check it out!</span>
     </a>

Classes and ids for CSS are easy to produce:

link_to "Articles", articles_path, id: "news", class: "article"
# => <a href="/articles" class="article" id="news">Articles</a>

Be careful when using the older argument style, as an extra literal hash is needed:

link_to "Articles", { controller: "articles" }, id: "news", class: "article"
# => <a href="/articles" class="article" id="news">Articles</a>

Leaving the hash off gives the wrong link:

link_to "WRONG!", controller: "articles", id: "news", class: "article"
# => <a href="/articles/index/news?class=article">WRONG!</a>

link_to can also produce links with anchors or query strings:

link_to "Comment wall", profile_path(@profile, anchor: "wall")
# => <a href="/profiles/1#wall">Comment wall</a>

link_to "Ruby on Rails search", controller: "searches", query: "ruby on rails"
# => <a href="/searches?query=ruby+on+rails">Ruby on Rails search</a>

link_to "Nonsense search", searches_path(foo: "bar", baz: "quux")
# => <a href="/searches?foo=bar&amp;baz=quux">Nonsense search</a>

The only option specific to link_to (:method) is used as follows:

link_to("Destroy", "http://www.example.com", method: :delete)
# => <a href='http://www.example.com' rel="nofollow" data-method="delete">Destroy</a>

You can also use custom data attributes using the :data option:

link_to "Visit Other Site", "http://www.rubyonrails.org/", data: { confirm: "Are you sure?" }
# => <a href="http://www.rubyonrails.org/" data-confirm="Are you sure?">Visit Other Site</a>

Also you can set any link attributes such as target, rel, type:

link_to "External link", "http://www.rubyonrails.org/", target: "_blank", rel: "nofollow"
# => <a href="http://www.rubyonrails.org/" target="_blank" rel="nofollow">External link</a>

# File actionview/lib/action_view/helpers/url_helper.rb, line 426
def link_to_if(condition, name, options = {}, html_options = {}, &block)
  if condition
    link_to(name, options, html_options)
  else
    if block_given?
      block.arity <= 1 ? capture(name, &block) : capture(name, options, html_options, &block)
    else
      ERB::Util.html_escape(name)
    end
  end
end

Creates a link tag of the given name using a URL created by the set of options if condition is true, otherwise only the name is returned. To specialize the default behavior, you can pass a block that accepts the name or the full argument list for link_to_unless (see the examples in link_to_unless).

Examples

<%= link_to_if(@current_user.nil?, "Login", { controller: "sessions", action: "new" }) %>
# If the user isn't logged in...
# => <a href="/sessions/new/">Login</a>

<%=
   link_to_if(@current_user.nil?, "Login", { controller: "sessions", action: "new" }) do
     link_to(@current_user.login, { controller: "accounts", action: "show", id: @current_user })
   end
%>
# If the user isn't logged in...
# => <a href="/sessions/new/">Login</a>
# If they are logged in...
# => <a href="/accounts/show/3">my_username</a>

# File actionview/lib/action_view/helpers/url_helper.rb, line 402
def link_to_unless(condition, name, options = {}, html_options = {}, &block)
  link_to_if !condition, name, options, html_options, &block
end

Creates a link tag of the given name using a URL created by the set of options unless condition is true, in which case only the name is returned. To specialize the default behavior (i.e., show a login link rather than just the plaintext link text), you can pass a block that accepts the name or the full argument list for link_to_unless.

Examples

<%= link_to_unless(@current_user.nil?, "Reply", { action: "reply" }) %>
# If the user is logged in...
# => <a href="/controller/reply/">Reply</a>

<%=
   link_to_unless(@current_user.nil?, "Reply", { action: "reply" }) do |name|
     link_to(name, { controller: "accounts", action: "signup" })
   end
%>
# If the user is logged in...
# => <a href="/controller/reply/">Reply</a>
# If not...
# => <a href="/accounts/signup">Reply</a>

# File actionview/lib/action_view/helpers/url_helper.rb, line 378
def link_to_unless_current(name, options = {}, html_options = {}, &block)
  link_to_unless current_page?(options), name, options, html_options, &block
end

Creates a link tag of the given name using a URL created by the set of options unless the current request URI is the same as the links, in which case only the name is returned (or the given block is yielded, if one exists). You can give link_to_unless_current a block which will specialize the default behavior (e.g., show a “Start Here” link rather than the link's text).

Examples

Let's say you have a navigation menu…

<ul id="navbar">
  <li><%= link_to_unless_current("Home", { action: "index" }) %></li>
  <li><%= link_to_unless_current("About Us", { action: "about" }) %></li>
</ul>

If in the “about” action, it will render…

<ul id="navbar">
  <li><a href="/controller/index">Home</a></li>
  <li>About Us</li>
</ul>

…but if in the “index” action, it will render:

<ul id="navbar">
  <li>Home</li>
  <li><a href="/controller/about">About Us</a></li>
</ul>

The implicit block given to link_to_unless_current is evaluated if the current action is the action given. So, if we had a comments page and wanted to render a “Go Back” link instead of a link to the comments page, we could do something like this…

<%=
    link_to_unless_current("Comment", { controller: "comments", action: "new" }) do
       link_to("Go back", { controller: "posts", action: "index" })
    end
 %>

# File actionview/lib/action_view/helpers/url_helper.rb, line 476
def mail_to(email_address, name = nil, html_options = {}, &block)
  html_options, name = name, nil if block_given?
  html_options = (html_options || {}).stringify_keys

  extras = %w{ cc bcc body subject reply_to }.map! { |item|
    option = html_options.delete(item).presence || next
    "#{item.dasherize}=#{ERB::Util.url_encode(option)}"
  }.compact
  extras = extras.empty? ? ''.freeze : '?' + extras.join('&')

  encoded_email_address = ERB::Util.url_encode(email_address).gsub("%40", "@")
  html_options["href"] = "mailto:#{encoded_email_address}#{extras}"

  content_tag("a".freeze, name || email_address, html_options, &block)
end

Creates a mailto link tag to the specified email_address, which is also used as the name of the link unless name is specified. Additional HTML attributes for the link can be passed in html_options.

mail_to has several methods for customizing the email itself by passing special keys to html_options.

Options

• :subject - Preset the subject line of the email.

• :body - Preset the body of the email.

• :cc - Carbon Copy additional recipients on the email.

• :bcc - Blind Carbon Copy additional recipients on the email.

• :reply_to - Preset the Reply-To field of the email.

Obfuscation

Prior to Rails 4.0, mail_to provided options for encoding the address in order to hinder email harvesters. To take advantage of these options, install the actionview-encoded_mail_to gem.

Examples

mail_to "[email protected]"
# => <a href="mailto:[email protected]">[email protected]</a>

mail_to "[email protected]", "My email"
# => <a href="mailto:[email protected]">My email</a>

mail_to "[email protected]", "My email", cc: "[email protected]",
         subject: "This is an example email"
# => <a href="mailto:[email protected][email protected]&subject=This%20is%20an%20example%20email">My email</a>

You can use a block as well if your link target is hard to fit into the name parameter. ERB example:

<%= mail_to "[email protected]" do %>
  <strong>Email me:</strong> <span>[email protected]</span>
<% end %>
# => <a href="mailto:[email protected]">
       <strong>Email me:</strong> <span>[email protected]</span>
     </a>