# 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.

### Public Instance Methods

_routes_context() click to toggle source

    # File lib/action_view/helpers/url_helper.rb, line 26
    def _routes_context
      controller
    end

button_to(name, options = {}, html_options = {}) 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` and `:confirm` modifiers 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` and `:put`. By default it will be `:post`.

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

- `: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.

- `: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

#### Examples¶ ↑

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

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

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

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

    # File lib/action_view/helpers/url_helper.rb, line 324
    def button_to(name, options = {}, html_options = {})
      html_options = html_options.stringify_keys
      convert_boolean_attributes!(html_options, %w( disabled ))

      method_tag = ''
      if (method = html_options.delete('method')) && %w{put delete}.include?(method.to_s)
        method_tag = tag('input', :type => 'hidden', :name => '_method', :value => method.to_s)
      end

      form_method = method.to_s == 'get' ? 'get' : 'post'
      form_options = html_options.delete('form') || {}
      form_options[:class] ||= html_options.delete('form_class') || 'button_to'

      remote = html_options.delete('remote')

      request_token_tag = ''
      if form_method == 'post' && protect_against_forgery?
        request_token_tag = tag(:input, :type => "hidden", :name => request_forgery_protection_token.to_s, :value => form_authenticity_token)
      end

      url = options.is_a?(String) ? options : self.url_for(options)
      name ||= url

      html_options = convert_options_to_data_attributes(options, html_options)

      html_options.merge!("type" => "submit", "value" => name)

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

      "#{tag(:form, form_options, true)}<div>#{method_tag}#{tag("input", html_options)}#{request_token_tag}</div></form>".html_safe
    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 `/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

Let’s say we’re in the `/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 `/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 588
    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?

      url_string = url_for(options)

      # 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
      if url_string.index("?")
        request_uri = request.fullpath
      else
        request_uri = request.path
      end

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

link_to(*args, &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 :confirm or :method,
      # is passed to url_for

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

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

#### Options¶ ↑

- `:confirm => 'question?'` - This will allow the unobtrusive JavaScript driver to prompt with the question specified. If the user accepts, the link is processed normally, otherwise no action is taken.

- `: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` 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?` 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

#### 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 two options specific to `link_to` (`:confirm` and `:method`) are used as follows:

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

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

    # File lib/action_view/helpers/url_helper.rb, line 231
    def link_to(*args, &block)
      if block_given?
        options      = args.first || {}
        html_options = args.second
        link_to(capture(&block), options, html_options)
      else
        name         = args[0]
        options      = args[1] || {}
        html_options = args[2]

        html_options = convert_options_to_data_attributes(options, html_options)
        url = url_for(options)

        href = html_options['href']
        tag_options = tag_options(html_options)

        href_attr = "href=\"#{ERB::Util.html_escape(url)}\"" unless href
        "<a #{href_attr}#{tag_options}>#{ERB::Util.html_escape(name || url)}</a>".html_safe
      end
    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 452
    def link_to_if(condition, name, options = {}, html_options = {}, &block)
      link_to_unless !condition, name, options, html_options, &block
    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 420
    def link_to_unless(condition, name, options = {}, html_options = {}, &block)
      if condition
        if block_given?
          block.arity <= 1 ? capture(name, &block) : capture(name, options, html_options, &block)
        else
          ERB::Util.html_escape(name)
        end
      else
        link_to(name, options, html_options)
      end
    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 396
    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 = {}) 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 hindering email harvesters and customizing the email itself by passing special keys to `html_options`.

#### Options¶ ↑

- `:encode` - This key will accept the strings "javascript" or "hex". Passing "javascript" will dynamically create and encode the mailto link then eval it into the DOM of the page. This method will not show the link on the page if the user has JavaScript disabled. Passing "hex" will hex encode the `email_address` before outputting the mailto link.

- `:replace_at` - When the link `name` isn't provided, the `email_address` is used for the link label. You can use this option to obfuscate the `email_address` by substituting the @ sign with the string given as the value.

- `:replace_dot` - When the link `name` isn't provided, the `email_address` is used for the link label. You can use this option to obfuscate the `email_address` by substituting the . in the email with the string given as the value.

- `: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.

#### Examples¶ ↑

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

    mail_to "me@domain.com", "My email", :encode => "javascript"
    # => <script type="text/javascript">eval(decodeURIComponent('%64%6f%63...%27%29%3b'))</script>

    mail_to "me@domain.com", "My email", :encode => "hex"
    # => <a href="mailto:%6d%65@%64%6f%6d%61%69%6e.%63%6f%6d">My email</a>

    mail_to "me@domain.com", nil, :replace_at => "_at_", :replace_dot => "_dot_", :class => "email"
    # => <a href="mailto:me@domain.com" class="email">me_at_domain_dot_com</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>

    # File lib/action_view/helpers/url_helper.rb, line 498
    def mail_to(email_address, name = nil, html_options = {})
      email_address = ERB::Util.html_escape(email_address)

      html_options = html_options.stringify_keys
      encode = html_options.delete("encode").to_s

      extras = %w{ cc bcc body subject }.map { |item|
        option = html_options.delete(item) || next
        "#{item}=#{Rack::Utils.escape(option).gsub("+", "%20")}"
      }.compact
      extras = extras.empty? ? '' : '?' + ERB::Util.html_escape(extras.join('&'))

      email_address_obfuscated = email_address.to_str
      email_address_obfuscated.gsub!(/@/, html_options.delete("replace_at")) if html_options.key?("replace_at")
      email_address_obfuscated.gsub!(/\./, html_options.delete("replace_dot")) if html_options.key?("replace_dot")
      case encode
      when "javascript"
        string = ''
        html   = content_tag("a", name || email_address_obfuscated.html_safe, html_options.merge("href" => "mailto:#{email_address}#{extras}".html_safe))
        html   = escape_javascript(html.to_str)
        "document.write('#{html}');".each_byte do |c|
          string << sprintf("%%%x", c)
        end
        "<script type=\"#{Mime::JS}\">eval(decodeURIComponent('#{string}'))</script>".html_safe
      when "hex"
        email_address_encoded = email_address_obfuscated.unpack('C*').map {|c|
          sprintf("&#%d;", c)
        }.join

        string = 'mailto:'.unpack('C*').map { |c|
          sprintf("&#%d;", c)
        }.join + email_address.unpack('C*').map { |c|
          char = c.chr
          char =~ /\w/ ? sprintf("%%%x", c) : char
        }.join

        content_tag "a", name || email_address_encoded.html_safe, html_options.merge("href" => "#{string}#{extras}".html_safe)
      else
        content_tag "a", name || email_address_obfuscated.html_safe, html_options.merge("href" => "mailto:#{email_address}#{extras}".html_safe)
      end
    end

url_for(options = {}) click to toggle source

Returns the URL for the set of `options` provided. This takes the same options as `url_for` in Action Controller (see the documentation for `ActionController::Base#url_for`). Note that by default `:only_path` is `true` so you’ll get the relative “/controller/action” instead of the fully qualified URL like “example.com/controller/action”.

#### Options¶ ↑

- `:anchor` - Specifies the anchor name to be appended to the path.

- `:only_path` - If true, returns the relative URL (omitting the protocol, host name, and port) (`true` by default unless `:host` is specified).

- `:trailing_slash` - If true, adds a trailing slash, as in "/archive/2005/". Note that this is currently not recommended since it breaks caching.

- `:host` - Overrides the default (current) host if provided.

- `:protocol` - Overrides the default (current) protocol if provided.

- `:user` - Inline HTTP authentication (only plucked out if `:password` is also present).

- `:password` - Inline HTTP authentication (only plucked out if `:user` is also present).

#### Relying on named routes¶ ↑

Passing a record (like an Active Record or Active Resource) instead of a Hash as the options parameter will trigger the named route for that record. The lookup will happen on the name of the class. So passing a Workshop object will attempt to use the `workshop_path` route. If you have a nested route, such as `admin_workshop_path` you’ll have to call that explicitly (it’s impossible for `url_for` to guess that route).

#### Examples¶ ↑

    <%= url_for(:action => 'index') %>
    # => /blog/

    <%= url_for(:action => 'find', :controller => 'books') %>
    # => /books/find

    <%= url_for(:action => 'login', :controller => 'members', :only_path => false, :protocol => 'https') %>
    # => https://www.example.com/members/login/

    <%= url_for(:action => 'play', :anchor => 'player') %>
    # => /messages/play/#player

    <%= url_for(:action => 'jump', :anchor => 'tax&ship') %>
    # => /testing/jump/#tax&ship

    <%= url_for(Workshop.new) %>
    # relies on Workshop answering a persisted? call (and in this case returning false)
    # => /workshops

    <%= url_for(@workshop) %>
    # calls @workshop.to_param which by default returns the id
    # => /workshops/5

    # to_param can be re-defined in a model to provide different URL names:
    # => /workshops/1-workshop-name

    <%= url_for("http://www.example.com") %>
    # => http://www.example.com

    <%= url_for(:back) %>
    # if request.env["HTTP_REFERER"] is set to "http://www.example.com"
    # => http://www.example.com

    <%= url_for(:back) %>
    # if request.env["HTTP_REFERER"] is not set or is blank
    # => javascript:history.back()

Calls superclass method ActionDispatch::Routing::UrlFor#url_for

    # File lib/action_view/helpers/url_helper.rb, line 100
    def url_for(options = {})
      options ||= {}
      case options
      when String
        options
      when Hash
        options = options.symbolize_keys.reverse_merge!(:only_path => options[:host].nil?)
        super
      when :back
        controller.request.env["HTTP_REFERER"] || 'javascript:history.back()'
      else
        polymorphic_path(options)
      end
    end

url_options() click to toggle source

Need to map default url options to controller one. def default_url_options(*args) #:nodoc:

    controller.send(:default_url_options, *args)

end

Calls superclass method ActionDispatch::Routing::UrlFor#url_options

    # File lib/action_view/helpers/url_helper.rb, line 35
    def url_options
      return super unless controller.respond_to?(:url_options)
      controller.url_options
    end