module ActionView::Helpers::UrlHelper - actionview-4.2.3 Documentation

# module ActionView::Helpers::UrlHelper

Provides a set of methods for making links and getting URLs that depend on the routing subsystem (see ActionDispatch::Routing). This allows you to use the same format for links in views and controllers.

### Constants

BUTTON_TAG_METHOD_VERBS

  This helper may be included in any class that includes the URL helpers of a routes (routes.url_helpers). Some methods provided here will only work in the context of a request (link_to_unless_current, for instance), which must be provided as a method called request on the context.

### Public Instance Methods

button_to(name = nil, options = nil, html_options = nil, &block) click to toggle source

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 lib/action_view/helpers/url_helper.rb, line 279
    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
      convert_boolean_attributes!(html_options, %w(disabled))

      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) : ''.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.merge!(method: form_method, action: url)
      form_options.merge!("data-remote" => "true") if remote

      request_token_tag = form_method == 'post' ? token_tag : ''

      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
        params.each do |param_name, value|
          inner_tags.safe_concat tag(:input, type: "hidden", name: param_name, value: value.to_param)
        end
      end
      content_tag('form', inner_tags, form_options)
    end

current_page?(options) click to toggle source

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` action.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    # File lib/action_view/helpers/url_helper.rb, line 525
    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)

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

link_to(name = nil, options = nil, html_options = nil, &block) click to toggle source

Creates a link tag 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 a link tag 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>

    # File lib/action_view/helpers/url_helper.rb, line 175
    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'] ||= url

      content_tag(:a, name || url, html_options, &block)
    end

link_to_if(condition, name, options = {}, html_options = {}, &block) click to toggle source

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 lib/action_view/helpers/url_helper.rb, line 407
    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

link_to_unless(condition, name, options = {}, html_options = {}, &block) click to toggle source

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 lib/action_view/helpers/url_helper.rb, line 383
    def link_to_unless(condition, name, options = {}, html_options = {}, &block)
      link_to_if !condition, name, options, html_options, &block
    end

link_to_unless_current(name, options = {}, html_options = {}, &block) click to toggle source

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 lib/action_view/helpers/url_helper.rb, line 359
    def link_to_unless_current(name, options = {}, html_options = {}, &block)
      link_to_unless current_page?(options), name, options, html_options, &block
    end

mail_to(email_address, name = nil, html_options = {}, &block) click to toggle source

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.

#### 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 "me@domain.com"
    # => <a href="mailto:me@domain.com">me@domain.com</a>

    mail_to "me@domain.com", "My email"
    # => <a href="mailto:me@domain.com">My email</a>

    mail_to "me@domain.com", "My email", cc: "ccaddress@domain.com",
             subject: "This is an example email"
    # => <a href="mailto:me@domain.com?cc=ccaddress@domain.com&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 "me@domain.com" do %>
      <strong>Email me:</strong> <span>me@domain.com</span>
    <% end %>
    # => <a href="mailto:me@domain.com">
           <strong>Email me:</strong> <span>me@domain.com</span>
         </a>

    # File lib/action_view/helpers/url_helper.rb, line 456
    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 }.map! { |item|
        option = html_options.delete(item) || next
        "#{item}=#{Rack::Utils.escape_path(option)}"
      }.compact
      extras = extras.empty? ? '' : '?' + extras.join('&')

      html_options["href"] = "mailto:#{email_address}#{extras}"

      content_tag(:a, name || email_address, html_options, &block)
    end

### Private Instance Methods

add_method_to_attributes!(html_options, method) click to toggle source

    # File lib/action_view/helpers/url_helper.rb, line 571
    def add_method_to_attributes!(html_options, method)
      if method && method.to_s.downcase != "get" && html_options["rel"] !~ /nofollow/
        html_options["rel"] = "#{html_options["rel"]} nofollow".lstrip
      end
      html_options["data-method"] = method
    end

convert_boolean_attributes!(html_options, bool_attrs) click to toggle source

Processes the `html_options` hash, converting the boolean attributes from true/false form into the form required by HTML/XHTML. (An attribute is considered to be boolean if its name is listed in the given `bool_attrs` array.)

More specifically, for each boolean attribute in `html_options` given as:

    "attr" => bool_value

if the associated `bool_value` evaluates to true, it is replaced with the attribute's name; otherwise the attribute is removed from the `html_options` hash. (See the XHTML 1.0 spec, section 4.5 “Attribute Minimization” for more: www.w3.org/TR/xhtml1/#h-4.5)

Returns the updated `html_options` hash, which is also modified in place.

Example:

    convert_boolean_attributes!( html_options,
                                 %w( checked disabled readonly ) )

    # File lib/action_view/helpers/url_helper.rb, line 601
    def convert_boolean_attributes!(html_options, bool_attrs)
      bool_attrs.each { |x| html_options[x] = x if html_options.delete(x) }
      html_options
    end

convert_options_to_data_attributes(options, html_options) click to toggle source

    # File lib/action_view/helpers/url_helper.rb, line 550
    def convert_options_to_data_attributes(options, html_options)
      if html_options
        html_options = html_options.stringify_keys
        html_options['data-remote'] = 'true' if link_to_remote_options?(options) || link_to_remote_options?(html_options)

        method  = html_options.delete('method')

        add_method_to_attributes!(html_options, method) if method

        html_options
      else
        link_to_remote_options?(options) ? {'data-remote' => 'true'} : {}
      end
    end

link_to_remote_options?(options) click to toggle source

    # File lib/action_view/helpers/url_helper.rb, line 565
    def link_to_remote_options?(options)
      if options.is_a?(Hash)
        options.delete('remote') || options.delete(:remote)
      end
    end

method_tag(method) click to toggle source

    # File lib/action_view/helpers/url_helper.rb, line 615
    def method_tag(method)
      tag('input', type: 'hidden', name: '_method', value: method.to_s)
    end

token_tag(token=nil) click to toggle source

    # File lib/action_view/helpers/url_helper.rb, line 606
    def token_tag(token=nil)
      if token != false && protect_against_forgery?
        token ||= form_authenticity_token
        tag(:input, type: "hidden", name: request_forgery_protection_token.to_s, value: token)
      else
        ''
      end
    end