Module: ActionView::Helpers::AssetTagHelper

Included in:
ActionView::Helpers
Defined in:
lib/action_view/helpers/asset_tag_helper.rb

Overview

This module provides methods for generating HTML that links views to assets such as images, javascripts, stylesheets, and feeds. These methods do not verify the assets exist before linking to them:

image_tag("rails.png")
# => <img alt="Rails" src="/images/rails.png?1230601161" />
stylesheet_link_tag("application")
# => <link href="/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />

Using asset hosts

By default, Rails links to these assets on the current host in the public folder, but you can direct Rails to link to assets from a dedicated asset server by setting ActionController::Base.asset_host in the application configuration, typically in config/environments/production.rb. For example, you’d define assets.example.com to be your asset host this way:

ActionController::Base.asset_host = "assets.example.com"

Helpers take that into account:

image_tag("rails.png")
# => <img alt="Rails" src="http://assets.example.com/images/rails.png?1230601161" />
stylesheet_link_tag("application")
# => <link href="http://assets.example.com/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />

Browsers typically open at most two simultaneous connections to a single host, which means your assets often have to wait for other assets to finish downloading. You can alleviate this by using a %d wildcard in the asset_host. For example, “assets%d.example.com”. If that wildcard is present Rails distributes asset requests among the corresponding four hosts “assets0.example.com”, …, “assets3.example.com”. With this trick browsers will open eight simultaneous connections rather than two.

image_tag("rails.png")
# => <img alt="Rails" src="http://assets0.example.com/images/rails.png?1230601161" />
stylesheet_link_tag("application")
# => <link href="http://assets2.example.com/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />

To do this, you can either setup four actual hosts, or you can use wildcard DNS to CNAME the wildcard to a single asset host. You can read more about setting up your DNS CNAME records from your ISP.

Note: This is purely a browser performance optimization and is not meant for server load balancing. See www.die.net/musings/page_load_time/ for background.

Alternatively, you can exert more control over the asset host by setting asset_host to a proc like this:

ActionController::Base.asset_host = Proc.new { |source|
  "http://assets#{source.hash % 2 + 1}.example.com"
}
image_tag("rails.png")
# => <img alt="Rails" src="http://assets1.example.com/images/rails.png?1230601161" />
stylesheet_link_tag("application")
# => <link href="http://assets2.example.com/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />

The example above generates “assets1.example.com” and “assets2.example.com”. This option is useful for example if you need fewer/more than four hosts, custom host names, etc.

As you see the proc takes a source parameter. That’s a string with the absolute path of the asset with any extensions and timestamps in place, for example “/images/rails.png?1230601161”.

 ActionController::Base.asset_host = Proc.new { |source|
   if source.starts_with?('/images')
     "http://images.example.com"
   else
     "http://assets.example.com"
   end
 }
image_tag("rails.png")
# => <img alt="Rails" src="http://images.example.com/images/rails.png?1230601161" />
stylesheet_link_tag("application")
# => <link href="http://assets.example.com/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />

Alternatively you may ask for a second parameter request. That one is particularly useful for serving assets from an SSL-protected page. The example proc below disables asset hosting for HTTPS connections, while still sending assets for plain HTTP requests from asset hosts. If you don’t have SSL certificates for each of the asset hosts this technique allows you to avoid warnings in the client about mixed media.

ActionController::Base.asset_host = Proc.new { |source, request|
  if request.ssl?
    "#{request.protocol}#{request.host_with_port}"
  else
    "#{request.protocol}assets.example.com"
  end
}

You can also implement a custom asset host object that responds to call and takes either one or two parameters just like the proc.

config.action_controller.asset_host = AssetHostingWithMinimumSsl.new(
  "http://asset%d.example.com", "https://asset1.example.com"
)

Customizing the asset path

By default, Rails appends asset’s timestamps to all asset paths. This allows you to set a cache-expiration date for the asset far into the future, but still be able to instantly invalidate it by simply updating the file (and hence updating the timestamp, which then updates the URL as the timestamp is part of that, which in turn busts the cache).

It’s the responsibility of the web server you use to set the far-future expiration date on cache assets that you need to take advantage of this feature. Here’s an example for Apache:

# Asset Expiration
ExpiresActive On
<FilesMatch "\.(ico|gif|jpe?g|png|js|css)$">
  ExpiresDefault "access plus 1 year"
</FilesMatch>

Also note that in order for this to work, all your application servers must return the same timestamps. This means that they must have their clocks synchronized. If one of them drifts out of sync, you’ll see different timestamps at random and the cache won’t work. In that case the browser will request the same assets over and over again even thought they didn’t change. You can use something like Live HTTP Headers for Firefox to verify that the cache is indeed working.

This strategy works well enough for most server setups and requires the least configuration, but if you deploy several application servers at different times - say to handle a temporary spike in load - then the asset time stamps will be out of sync. In a setup like this you may want to set the way that asset paths are generated yourself.

Altering the asset paths that Rails generates can be done in two ways. The easiest is to define the RAILS_ASSET_ID environment variable. The contents of this variable will always be used in preference to calculated timestamps. A more complex but flexible way is to set ActionController::Base.config.asset_path to a proc that takes the unmodified asset path and returns the path needed for your asset caching to work. Typically you’d do something like this in config/environments/production.rb:

# Normally you'd calculate RELEASE_NUMBER at startup.
RELEASE_NUMBER = 12345
config.action_controller.asset_path_template = proc { |asset_path|
  "/release-#{RELEASE_NUMBER}#{asset_path}"
}

This example would cause the following behaviour on all servers no matter when they were deployed:

image_tag("rails.png")
# => <img alt="Rails" src="/release-12345/images/rails.png" />
stylesheet_link_tag("application")
# => <link href="/release-12345/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" type="text/css" />

Changing the asset_path does require that your web servers have knowledge of the asset template paths that you rewrite to so it’s not suitable for out-of-the-box use. To use the example given above you could use something like this in your Apache VirtualHost configuration:

<LocationMatch "^/release-\d+/(images|javascripts|stylesheets)/.*$">
  # Some browsers still send conditional-GET requests if there's a
  # Last-Modified header or an ETag header even if they haven't
  # reached the expiry date sent in the Expires header.
  Header unset Last-Modified
  Header unset ETag
  FileETag None

  # Assets requested using a cache-busting filename should be served
  # only once and then cached for a really long time. The HTTP/1.1
  # spec frowns on hugely-long expiration times though and suggests
  # that assets which never expire be served with an expiration date
  # 1 year from access.
  ExpiresActive On
  ExpiresDefault "access plus 1 year"
</LocationMatch>

# We use cached-busting location names with the far-future expires
# headers to ensure that if a file does change it can force a new
# request. The actual asset filenames are still the same though so we
# need to rewrite the location from the cache-busting location to the
# real asset location so that we can serve it.
RewriteEngine On
RewriteRule ^/release-\d+/(images|javascripts|stylesheets)/(.*)$ /$1/$2 [L]

Constant Summary collapse

@@javascript_expansions = 
{ }
@@stylesheet_expansions = 
{}

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.register_javascript_expansion(expansions) ⇒ Object

Register one or more javascript files to be included when symbol is passed to javascript_include_tag. This method is typically intended to be called from plugin initialization to register javascript files that the plugin installed in public/javascripts.

ActionView::Helpers::AssetTagHelper.register_javascript_expansion :monkey => ["head", "body", "tail"]

javascript_include_tag :monkey # =>
  <script type="text/javascript" src="/javascripts/head.js"></script>
  <script type="text/javascript" src="/javascripts/body.js"></script>
  <script type="text/javascript" src="/javascripts/tail.js"></script>



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 377

def self.register_javascript_expansion(expansions)
  expansions.each do |key, values|
    @@javascript_expansions[key] = (@@javascript_expansions[key] || []) | Array(values)
  end
end

.register_javascript_include_default(*args) ⇒ Object 



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 406

def self.register_javascript_include_default(*args)
  ActiveSupport::Deprecation.warn "register_javascript_include_default is deprecated. Please " \
    "manipulate config.action_view.javascript_expansions[:defaults] directly", caller
  self.javascript_expansions[:defaults].concat args
end

.register_stylesheet_expansion(expansions) ⇒ Object

Register one or more stylesheet files to be included when symbol is passed to stylesheet_link_tag. This method is typically intended to be called from plugin initialization to register stylesheet files that the plugin installed in public/stylesheets.

ActionView::Helpers::AssetTagHelper.register_stylesheet_expansion :monkey => ["head", "body", "tail"]

stylesheet_link_tag :monkey # =>
  <link href="/stylesheets/head.css"  media="screen" rel="stylesheet" type="text/css" />
  <link href="/stylesheets/body.css"  media="screen" rel="stylesheet" type="text/css" />
  <link href="/stylesheets/tail.css"  media="screen" rel="stylesheet" type="text/css" />



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 394

def self.register_stylesheet_expansion(expansions)
  expansions.each do |key, values|
    @@stylesheet_expansions[key] = (@@stylesheet_expansions[key] || []) | Array(values)
  end
end

.reset_javascript_include_default ⇒ Object 



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 400

def self.reset_javascript_include_default
  ActiveSupport::Deprecation.warn "reset_javascript_include_default is deprecated. Please manipulate " \
    "config.action_view.javascript_expansions[:defaults] directly", caller
  self.javascript_expansions[:defaults] = ['prototype', 'effects', 'dragdrop', 'controls', 'rails']
end

Instance Method Details

#audio_path(source) ⇒ Object Also known as: path_to_audio

Computes the path to an audio asset in the public audios directory. Full paths from the document root will be passed through. Used internally by audio_tag to build the audio path.

Examples

audio_path("horse")                                            # => /audios/horse
audio_path("horse.wav")                                        # => /audios/horse.avi
audio_path("sounds/horse.wav")                                 # => /audios/sounds/horse.avi
audio_path("/sounds/horse.wav")                                # => /sounds/horse.avi
audio_path("http://www.railsapplication.com/sounds/horse.wav") # => http://www.railsapplication.com/sounds/horse.wav



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 594

def audio_path(source)
  compute_public_path(source, 'audios')
end

#audio_tag(source, options = {}) ⇒ Object

Returns an html audio tag for the source. The source can be full path or file that exists in your public audios directory.

Examples

audio_tag("sound")  # =>
  <audio src="/audios/sound" />
audio_tag("sound.wav")  # =>
  <audio src="/audios/sound.wav" />
audio_tag("sound.wav", :autoplay => true, :controls => true)  # =>
  <audio autoplay="autoplay" controls="controls" src="/audios/sound.wav" />



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 716

def audio_tag(source, options = {})
  options.symbolize_keys!
  options[:src] = path_to_audio(source)
  tag("audio", options)
end

#auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {}) ⇒ Object

Returns a link tag that browsers and news readers can use to auto-detect an RSS or ATOM feed. The type can either be :rss (default) or :atom. Control the link options in url_for format using the url_options. You can modify the LINK tag itself in tag_options.

Options

  • :rel - Specify the relation of this link, defaults to “alternate”

  • :type - Override the auto-generated mime type

  • :title - Specify the title of the link, defaults to the type

Examples

auto_discovery_link_tag # =>
   <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/controller/action" />
auto_discovery_link_tag(:atom) # =>
   <link rel="alternate" type="application/atom+xml" title="ATOM" href="http://www.currenthost.com/controller/action" />
auto_discovery_link_tag(:rss, {:action => "feed"}) # =>
   <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/controller/feed" />
auto_discovery_link_tag(:rss, {:action => "feed"}, {:title => "My RSS"}) # =>
   <link rel="alternate" type="application/rss+xml" title="My RSS" href="http://www.currenthost.com/controller/feed" />
auto_discovery_link_tag(:rss, {:controller => "news", :action => "feed"}) # =>
   <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.currenthost.com/news/feed" />
auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", {:title => "Example RSS"}) # =>
   <link rel="alternate" type="application/rss+xml" title="Example RSS" href="http://www.example.com/feed" />



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 234

def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})
  tag(
    "link",
    "rel"   => tag_options[:rel] || "alternate",
    "type"  => tag_options[:type] || Mime::Type.lookup_by_extension(type.to_s).to_s,
    "title" => tag_options[:title] || type.to_s.upcase,
    "href"  => url_options.is_a?(Hash) ? url_for(url_options.merge(:only_path => false)) : url_options
  )
end

#favicon_link_tag(source = '/favicon.ico', options = {}) ⇒ Object

Web browsers cache favicons. If you just throw a favicon.ico into the document root of your application and it changes later, clients that have it in their cache won’t see the update. Using this helper prevents that because it appends an asset ID:

<%= favicon_link_tag %>

generates

<link href="/favicon.ico?4649789979" rel="shortcut icon" type="image/vnd.microsoft.icon" />

You may specify a different file in the first argument:

<%= favicon_link_tag 'favicon.ico' %>

That’s passed to path_to_image as is, so it gives

<link href="/images/favicon.ico?4649789979" rel="shortcut icon" type="image/vnd.microsoft.icon" />

The helper accepts an additional options hash where you can override “rel” and “type”.

For example, Mobile Safari looks for a different LINK tag, pointing to an image that will be used if you add the page to the home screen of an iPod Touch, iPhone, or iPad. The following call would generate such a tag:

<%= favicon_link_tag 'mb-icon.png', :rel => 'apple-touch-icon', :type => 'image/png' %>



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 543

def favicon_link_tag(source='/favicon.ico', options={})
  tag('link', {
    :rel  => 'shortcut icon',
    :type => 'image/vnd.microsoft.icon',
    :href => path_to_image(source)
  }.merge(options.symbolize_keys))
end

#image_path(source) ⇒ Object Also known as: path_to_image

Computes the path to an image asset in the public images directory. Full paths from the document root will be passed through. Used internally by image_tag to build the image path:

image_path("edit")                                         # => "/images/edit"
image_path("edit.png")                                     # => "/images/edit.png"
image_path("icons/edit.png")                               # => "/images/icons/edit.png"
image_path("/icons/edit.png")                              # => "/icons/edit.png"
image_path("http://www.railsapplication.com/img/edit.png") # => "http://www.railsapplication.com/img/edit.png"

If you have images as application resources this method may conflict with their named routes. The alias path_to_image is provided to avoid that. Rails uses the alias internally, and plugin authors are encouraged to do so.



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 564

def image_path(source)
  compute_public_path(source, 'images')
end

#image_tag(source, options = {}) ⇒ Object

Returns an html image tag for the source. The source can be a full path or a file that exists in your public images directory.

Options

You can add HTML attributes using the options. The options supports three additional keys for convenience and conformance:

  • :alt - If no alt text is given, the file name part of the source is used (capitalized and without the extension)

  • :size - Supplied as “WidthxHeight”, so “30x45” becomes width=“30” and height=“45”. :size will be ignored if the value is not in the correct format.

  • :mouseover - Set an alternate image to be used when the onmouseover event is fired, and sets the original image to be replaced onmouseout. This can be used to implement an easy image toggle that fires on onmouseover.

Examples

image_tag("icon")  # =>
  <img src="/images/icon" alt="Icon" />
image_tag("icon.png")  # =>
  <img src="/images/icon.png" alt="Icon" />
image_tag("icon.png", :size => "16x10", :alt => "Edit Entry")  # =>
  <img src="/images/icon.png" width="16" height="10" alt="Edit Entry" />
image_tag("/icons/icon.gif", :size => "16x16")  # =>
  <img src="/icons/icon.gif" width="16" height="16" alt="Icon" />
image_tag("/icons/icon.gif", :height => '32', :width => '32') # =>
  <img alt="Icon" height="32" src="/icons/icon.gif" width="32" />
image_tag("/icons/icon.gif", :class => "menu_icon") # =>
  <img alt="Icon" class="menu_icon" src="/icons/icon.gif" />
image_tag("mouse.png", :mouseover => "/images/mouse_over.png") # =>
  <img src="/images/mouse.png" onmouseover="this.src='/images/mouse_over.png'" onmouseout="this.src='/images/mouse.png'" alt="Mouse" />
image_tag("mouse.png", :mouseover => image_path("mouse_over.png")) # =>
  <img src="/images/mouse.png" onmouseover="this.src='/images/mouse_over.png'" onmouseout="this.src='/images/mouse.png'" alt="Mouse" />



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 632

def image_tag(source, options = {})
  options.symbolize_keys!

  src = options[:src] = path_to_image(source)

  unless src =~ /^cid:/
    options[:alt] = options.fetch(:alt){ File.basename(src, '.*').capitalize }
  end

  if size = options.delete(:size)
    options[:width], options[:height] = size.split("x") if size =~ %r{^\d+x\d+$}
  end

  if mouseover = options.delete(:mouseover)
    options[:onmouseover] = "this.src='#{path_to_image(mouseover)}'"
    options[:onmouseout]  = "this.src='#{src}'"
  end

  tag("img", options)
end

#javascript_include_tag(*sources) ⇒ Object

Returns an html script tag for each of the sources provided. You can pass in the filename (.js extension is optional) of javascript files that exist in your public/javascripts directory for inclusion into the current page or you can pass the full path relative to your document root. To include the Prototype and Scriptaculous javascript libraries in your application, pass :defaults as the source. When using :defaults, if an application.js file exists in your public javascripts directory, it will be included as well. You can modify the html attributes of the script tag by passing a hash as the last argument.

Examples

javascript_include_tag "xmlhr" # =>
  <script type="text/javascript" src="/javascripts/xmlhr.js"></script>

javascript_include_tag "xmlhr.js" # =>
  <script type="text/javascript" src="/javascripts/xmlhr.js"></script>

javascript_include_tag "common.javascript", "/elsewhere/cools" # =>
  <script type="text/javascript" src="/javascripts/common.javascript"></script>
  <script type="text/javascript" src="/elsewhere/cools.js"></script>

javascript_include_tag "http://www.railsapplication.com/xmlhr" # =>
  <script type="text/javascript" src="http://www.railsapplication.com/xmlhr.js"></script>

javascript_include_tag "http://www.railsapplication.com/xmlhr.js" # =>
  <script type="text/javascript" src="http://www.railsapplication.com/xmlhr.js"></script>

javascript_include_tag :defaults # =>
  <script type="text/javascript" src="/javascripts/prototype.js"></script>
  <script type="text/javascript" src="/javascripts/effects.js"></script>
  ...
  <script type="text/javascript" src="/javascripts/application.js"></script>

  • The application.js file is only referenced if it exists

Though it’s not really recommended practice, if you need to extend the default JavaScript set for any reason (e.g., you’re going to be using a certain .js file in every action), then take a look at the register_javascript_include_default method.

You can also include all javascripts in the javascripts directory using :all as the source:

javascript_include_tag :all # =>
  <script type="text/javascript" src="/javascripts/prototype.js"></script>
  <script type="text/javascript" src="/javascripts/effects.js"></script>
  ...
  <script type="text/javascript" src="/javascripts/application.js"></script>
  <script type="text/javascript" src="/javascripts/shop.js"></script>
  <script type="text/javascript" src="/javascripts/checkout.js"></script>

Note that the default javascript files will be included first. So Prototype and Scriptaculous are available to all subsequently included files.

If you want Rails to search in all the subdirectories under javascripts, you should explicitly set :recursive:

javascript_include_tag :all, :recursive => true

Caching multiple javascripts into one

You can also cache multiple javascripts into one file, which requires less HTTP connections to download and can better be compressed by gzip (leading to faster transfers). Caching will only happen if config.perform_caching is set to true (which is the case by default for the Rails production environment, but not for the development environment).

Examples

javascript_include_tag :all, :cache => true # when config.perform_caching is false =>
  <script type="text/javascript" src="/javascripts/prototype.js"></script>
  <script type="text/javascript" src="/javascripts/effects.js"></script>
  ...
  <script type="text/javascript" src="/javascripts/application.js"></script>
  <script type="text/javascript" src="/javascripts/shop.js"></script>
  <script type="text/javascript" src="/javascripts/checkout.js"></script>

javascript_include_tag :all, :cache => true # when config.perform_caching is true =>
  <script type="text/javascript" src="/javascripts/all.js"></script>

javascript_include_tag "prototype", "cart", "checkout", :cache => "shop" # when config.perform_caching is false =>
  <script type="text/javascript" src="/javascripts/prototype.js"></script>
  <script type="text/javascript" src="/javascripts/cart.js"></script>
  <script type="text/javascript" src="/javascripts/checkout.js"></script>

javascript_include_tag "prototype", "cart", "checkout", :cache => "shop" # when config.perform_caching is true =>
  <script type="text/javascript" src="/javascripts/shop.js"></script>

The :recursive option is also available for caching:

javascript_include_tag :all, :cache => true, :recursive => true



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 345

def javascript_include_tag(*sources)
  options = sources.extract_options!.stringify_keys
  concat  = options.delete("concat")
  cache   = concat || options.delete("cache")
  recursive = options.delete("recursive")

  if concat || (config.perform_caching && cache)
    joined_javascript_name = (cache == true ? "all" : cache) + ".js"
    joined_javascript_path = File.join(joined_javascript_name[/^#{File::SEPARATOR}/] ? config.assets_dir : config.javascripts_dir, joined_javascript_name)

    unless config.perform_caching && File.exists?(joined_javascript_path)
      write_asset_file_contents(joined_javascript_path, compute_javascript_paths(sources, recursive))
    end
    javascript_src_tag(joined_javascript_name, options)
  else
    sources = expand_javascript_sources(sources, recursive)
    ensure_javascript_sources!(sources) if cache
    sources.collect { |source| javascript_src_tag(source, options) }.join("\n").html_safe
  end
end

#javascript_path(source) ⇒ Object Also known as: path_to_javascript

Computes the path to a javascript asset in the public javascripts directory. If the source filename has no extension, .js will be appended (except for explicit URIs) Full paths from the document root will be passed through. Used internally by javascript_include_tag to build the script path.

Examples

javascript_path "xmlhr" # => /javascripts/xmlhr.js
javascript_path "dir/xmlhr.js" # => /javascripts/dir/xmlhr.js
javascript_path "/dir/xmlhr" # => /dir/xmlhr.js
javascript_path "http://www.railsapplication.com/js/xmlhr" # => http://www.railsapplication.com/js/xmlhr
javascript_path "http://www.railsapplication.com/js/xmlhr.js" # => http://www.railsapplication.com/js/xmlhr.js



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 255

def javascript_path(source)
  compute_public_path(source, 'javascripts', 'js')
end

#stylesheet_link_tag(*sources) ⇒ Object

Returns a stylesheet link tag for the sources specified as arguments. If you don’t specify an extension, .css will be appended automatically. You can modify the link attributes by passing a hash as the last argument.

Examples

stylesheet_link_tag "style" # =>
  <link href="/stylesheets/style.css" media="screen" rel="stylesheet" type="text/css" />

stylesheet_link_tag "style.css" # =>
  <link href="/stylesheets/style.css" media="screen" rel="stylesheet" type="text/css" />

stylesheet_link_tag "http://www.railsapplication.com/style.css" # =>
  <link href="http://www.railsapplication.com/style.css" media="screen" rel="stylesheet" type="text/css" />

stylesheet_link_tag "style", :media => "all" # =>
  <link href="/stylesheets/style.css" media="all" rel="stylesheet" type="text/css" />

stylesheet_link_tag "style", :media => "print" # =>
  <link href="/stylesheets/style.css" media="print" rel="stylesheet" type="text/css" />

stylesheet_link_tag "random.styles", "/css/stylish" # =>
  <link href="/stylesheets/random.styles" media="screen" rel="stylesheet" type="text/css" />
  <link href="/css/stylish.css" media="screen" rel="stylesheet" type="text/css" />

You can also include all styles in the stylesheets directory using :all as the source:

stylesheet_link_tag :all # =>
  <link href="/stylesheets/style1.css"  media="screen" rel="stylesheet" type="text/css" />
  <link href="/stylesheets/styleB.css"  media="screen" rel="stylesheet" type="text/css" />
  <link href="/stylesheets/styleX2.css" media="screen" rel="stylesheet" type="text/css" />

If you want Rails to search in all the subdirectories under stylesheets, you should explicitly set :recursive:

stylesheet_link_tag :all, :recursive => true

Caching multiple stylesheets into one

You can also cache multiple stylesheets into one file, which requires less HTTP connections and can better be compressed by gzip (leading to faster transfers). Caching will only happen if config.perform_caching is set to true (which is the case by default for the Rails production environment, but not for the development environment). Examples:

Examples

stylesheet_link_tag :all, :cache => true # when config.perform_caching is false =>
  <link href="/stylesheets/style1.css"  media="screen" rel="stylesheet" type="text/css" />
  <link href="/stylesheets/styleB.css"  media="screen" rel="stylesheet" type="text/css" />
  <link href="/stylesheets/styleX2.css" media="screen" rel="stylesheet" type="text/css" />

stylesheet_link_tag :all, :cache => true # when config.perform_caching is true =>
  <link href="/stylesheets/all.css"  media="screen" rel="stylesheet" type="text/css" />

stylesheet_link_tag "shop", "cart", "checkout", :cache => "payment" # when config.perform_caching is false =>
  <link href="/stylesheets/shop.css"  media="screen" rel="stylesheet" type="text/css" />
  <link href="/stylesheets/cart.css"  media="screen" rel="stylesheet" type="text/css" />
  <link href="/stylesheets/checkout.css" media="screen" rel="stylesheet" type="text/css" />

stylesheet_link_tag "shop", "cart", "checkout", :cache => "payment" # when config.perform_caching is true =>
  <link href="/stylesheets/payment.css"  media="screen" rel="stylesheet" type="text/css" />

The :recursive option is also available for caching:

stylesheet_link_tag :all, :cache => true, :recursive => true

To force concatenation (even in development mode) set :concat to true. This is useful if you have too many stylesheets for IE to load.

stylesheet_link_tag :all, :concat => true



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 496

def stylesheet_link_tag(*sources)
  options = sources.extract_options!.stringify_keys
  concat  = options.delete("concat")
  cache   = concat || options.delete("cache")
  recursive = options.delete("recursive")

  if concat || (config.perform_caching && cache)
    joined_stylesheet_name = (cache == true ? "all" : cache) + ".css"
    joined_stylesheet_path = File.join(joined_stylesheet_name[/^#{File::SEPARATOR}/] ? config.assets_dir : config.stylesheets_dir, joined_stylesheet_name)

    unless config.perform_caching && File.exists?(joined_stylesheet_path)
      write_asset_file_contents(joined_stylesheet_path, compute_stylesheet_paths(sources, recursive))
    end
    stylesheet_tag(joined_stylesheet_name, options)
  else
    sources = expand_stylesheet_sources(sources, recursive)
    ensure_stylesheet_sources!(sources) if cache
    sources.collect { |source| stylesheet_tag(source, options) }.join("\n").html_safe
  end
end

#stylesheet_path(source) ⇒ Object Also known as: path_to_stylesheet

Computes the path to a stylesheet asset in the public stylesheets directory. If the source filename has no extension, .css will be appended (except for explicit URIs). Full paths from the document root will be passed through. Used internally by stylesheet_link_tag to build the stylesheet path.

Examples

stylesheet_path "style" # => /stylesheets/style.css
stylesheet_path "dir/style.css" # => /stylesheets/dir/style.css
stylesheet_path "/dir/style.css" # => /dir/style.css
stylesheet_path "http://www.railsapplication.com/css/style" # => http://www.railsapplication.com/css/style
stylesheet_path "http://www.railsapplication.com/css/style.css" # => http://www.railsapplication.com/css/style.css



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 423

def stylesheet_path(source)
  compute_public_path(source, 'stylesheets', 'css')
end

#video_path(source) ⇒ Object Also known as: path_to_video

Computes the path to a video asset in the public videos directory. Full paths from the document root will be passed through. Used internally by video_tag to build the video path.

Examples

video_path("hd")                                            # => /videos/hd
video_path("hd.avi")                                        # => /videos/hd.avi
video_path("trailers/hd.avi")                               # => /videos/trailers/hd.avi
video_path("/trailers/hd.avi")                              # => /trailers/hd.avi
video_path("http://www.railsapplication.com/vid/hd.avi") # => http://www.railsapplication.com/vid/hd.avi



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 579

def video_path(source)
  compute_public_path(source, 'videos')
end

#video_tag(sources, options = {}) ⇒ Object

Returns an html video tag for the sources. If sources is a string, a single video tag will be returned. If sources is an array, a video tag with nested source tags for each source will be returned. The sources can be full paths or files that exists in your public videos directory.

Options

You can add HTML attributes using the options. The options supports two additional keys for convenience and conformance:

  • :poster - Set an image (like a screenshot) to be shown before the video loads. The path is calculated like the src of image_tag.

  • :size - Supplied as “WidthxHeight”, so “30x45” becomes width=“30” and height=“45”. :size will be ignored if the value is not in the correct format.

Examples

video_tag("trailer")  # =>
  <video src="/videos/trailer" />
video_tag("trailer.ogg")  # =>
  <video src="/videos/trailer.ogg" />
video_tag("trailer.ogg", :controls => true, :autobuffer => true)  # =>
  <video autobuffer="autobuffer" controls="controls" src="/videos/trailer.ogg" />
video_tag("trailer.m4v", :size => "16x10", :poster => "screenshot.png")  # =>
  <video src="/videos/trailer.m4v" width="16" height="10" poster="/images/screenshot.png" />
video_tag("/trailers/hd.avi", :size => "16x16")  # =>
  <video src="/trailers/hd.avi" width="16" height="16" />
video_tag("/trailers/hd.avi", :height => '32', :width => '32') # =>
  <video height="32" src="/trailers/hd.avi" width="32" />
video_tag(["trailer.ogg", "trailer.flv"]) # =>
  <video><source src="trailer.ogg" /><source src="trailer.ogg" /><source src="trailer.flv" /></video>
video_tag(["trailer.ogg", "trailer.flv"] :size => "160x120") # =>
  <video height="120" width="160"><source src="trailer.ogg" /><source src="trailer.flv" /></video>



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# File 'lib/action_view/helpers/asset_tag_helper.rb', line 686

def video_tag(sources, options = {})
  options.symbolize_keys!

  options[:poster] = path_to_image(options[:poster]) if options[:poster]

  if size = options.delete(:size)
    options[:width], options[:height] = size.split("x") if size =~ %r{^\d+x\d+$}
  end

  if sources.is_a?(Array)
    content_tag("video", options) do
      sources.map { |source| tag("source", :src => source) }.join.html_safe
    end
  else
    options[:src] = path_to_video(sources)
    tag("video", options)
  end
end