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ActionView::Helpers::AssetTagHelper

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]

Public Class Methods

register_javascript_expansion(expansions) click to toggle source

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>
     # File lib/action_view/helpers/asset_tag_helper.rb, line 377
377:       def self.register_javascript_expansion(expansions)
378:         @@javascript_expansions.merge!(expansions)
379:       end
register_javascript_include_default(*args) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 402
402:       def self.register_javascript_include_default(*args)
403:         ActiveSupport::Deprecation.warn "register_javascript_include_default is deprecated. Please "            "manipulate config.action_view.javascript_expansions[:defaults] directly", caller
404:         self.javascript_expansions[:defaults].concat args
405:       end
register_stylesheet_expansion(expansions) click to toggle source

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" />
     # File lib/action_view/helpers/asset_tag_helper.rb, line 392
392:       def self.register_stylesheet_expansion(expansions)
393:         @@stylesheet_expansions.merge!(expansions)
394:       end
reset_javascript_include_default() click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 396
396:       def self.reset_javascript_include_default
397:         ActiveSupport::Deprecation.warn "reset_javascript_include_default is deprecated. Please manipulate "            "config.action_view.javascript_expansions[:defaults] directly", caller
398:         self.javascript_expansions[:defaults] = ['prototype', 'effects', 'dragdrop', 'controls', 'rails']
399:       end

Public Instance Methods

audio_path(source) click to toggle source

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
     # File lib/action_view/helpers/asset_tag_helper.rb, line 590
590:       def audio_path(source)
591:         compute_public_path(source, 'audios')
592:       end
Also aliased as: path_to_audio
audio_tag(source, options = {}) click to toggle source

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" />
     # File lib/action_view/helpers/asset_tag_helper.rb, line 712
712:       def audio_tag(source, options = {})
713:         options.symbolize_keys!
714:         options[:src] = path_to_audio(source)
715:         tag("audio", options)
716:       end
image_path(source) click to toggle source

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.

     # File lib/action_view/helpers/asset_tag_helper.rb, line 560
560:       def image_path(source)
561:         compute_public_path(source, 'images')
562:       end
Also aliased as: path_to_image
image_tag(source, options = {}) click to toggle source

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 “{Width}x{Height}”, 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" />
     # File lib/action_view/helpers/asset_tag_helper.rb, line 628
628:       def image_tag(source, options = {})
629:         options.symbolize_keys!
630: 
631:         src = options[:src] = path_to_image(source)
632: 
633:         unless src =~ /^cid:/
634:           options[:alt] = options.fetch(:alt){ File.basename(src, '.*').capitalize }
635:         end
636: 
637:         if size = options.delete(:size)
638:           options[:width], options[:height] = size.split("x") if size =~ %{^\d+x\d+$}
639:         end
640: 
641:         if mouseover = options.delete(:mouseover)
642:           options[:onmouseover] = "this.src='#{path_to_image(mouseover)}'"
643:           options[:onmouseout]  = "this.src='#{src}'"
644:         end
645: 
646:         tag("img", options)
647:       end
javascript_include_tag(*sources) click to toggle source

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
     # File lib/action_view/helpers/asset_tag_helper.rb, line 345
345:       def javascript_include_tag(*sources)
346:         options = sources.extract_options!.stringify_keys
347:         concat  = options.delete("concat")
348:         cache   = concat || options.delete("cache")
349:         recursive = options.delete("recursive")
350: 
351:         if concat || (config.perform_caching && cache)
352:           joined_javascript_name = (cache == true ? "all" : cache) + ".js"
353:           joined_javascript_path = File.join(joined_javascript_name[/^#{File::SEPARATOR}/] ? config.assets_dir : config.javascripts_dir, joined_javascript_name)
354: 
355:           unless config.perform_caching && File.exists?(joined_javascript_path)
356:             write_asset_file_contents(joined_javascript_path, compute_javascript_paths(sources, recursive))
357:           end
358:           javascript_src_tag(joined_javascript_name, options)
359:         else
360:           sources = expand_javascript_sources(sources, recursive)
361:           ensure_javascript_sources!(sources) if cache
362:           sources.collect { |source| javascript_src_tag(source, options) }.join("\n").html_safe
363:         end
364:       end
javascript_path(source) click to toggle source

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
     # File lib/action_view/helpers/asset_tag_helper.rb, line 255
255:       def javascript_path(source)
256:         compute_public_path(source, 'javascripts', 'js')
257:       end
Also aliased as: path_to_javascript
path_to_audio(source) click to toggle source
Alias for: audio_path
path_to_image(source) click to toggle source
Alias for: image_path
path_to_javascript(source) click to toggle source
Alias for: javascript_path
path_to_stylesheet(source) click to toggle source
Alias for: stylesheet_path
path_to_video(source) click to toggle source
Alias for: video_path
stylesheet_path(source) click to toggle source

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
     # File lib/action_view/helpers/asset_tag_helper.rb, line 419
419:       def stylesheet_path(source)
420:         compute_public_path(source, 'stylesheets', 'css')
421:       end
Also aliased as: path_to_stylesheet
video_path(source) click to toggle source

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
     # File lib/action_view/helpers/asset_tag_helper.rb, line 575
575:       def video_path(source)
576:         compute_public_path(source, 'videos')
577:       end
Also aliased as: path_to_video
video_tag(sources, options = {}) click to toggle source

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 “{Width}x{Height}”, 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>
     # File lib/action_view/helpers/asset_tag_helper.rb, line 682
682:       def video_tag(sources, options = {})
683:         options.symbolize_keys!
684: 
685:         options[:poster] = path_to_image(options[:poster]) if options[:poster]
686: 
687:         if size = options.delete(:size)
688:           options[:width], options[:height] = size.split("x") if size =~ %{^\d+x\d+$}
689:         end
690: 
691:         if sources.is_a?(Array)
692:           content_tag("video", options) do
693:             sources.map { |source| tag("source", :src => source) }.join.html_safe
694:           end
695:         else
696:           options[:src] = path_to_video(sources)
697:           tag("video", options)
698:         end
699:       end

Private Instance Methods

asset_file_path(path) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 898
898:         def asset_file_path(path)
899:           File.join(config.assets_dir, path.split('?').first)
900:         end
asset_file_path!(path) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 902
902:         def asset_file_path!(path)
903:           unless is_uri?(path)
904:             absolute_path = asset_file_path(path)
905:             raise(Errno::ENOENT, "Asset file not found at '#{absolute_path}'" ) unless File.exist?(absolute_path)
906:             return absolute_path
907:           end
908:         end
collect_asset_files(*path) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 910
910:         def collect_asset_files(*path)
911:           dir = path.first
912: 
913:           Dir[File.join(*path.compact)].collect do |file|
914:             file[-(file.size - dir.size - 1)..1].sub(/\.\w+$/, '')
915:           end.sort
916:         end
compute_asset_host(source) click to toggle source

Pick an asset host for this source. Returns nil if no host is set, the host if no wildcard is set, the host interpolated with the numbers 0-3 if it contains %d (the number is the source hash mod 4), or the value returned from invoking the proc if it’s a proc or the value from invoking call if it’s an object responding to call.

     # File lib/action_view/helpers/asset_tag_helper.rb, line 762
762:         def compute_asset_host(source)
763:           if host = config.asset_host
764:             if host.is_a?(Proc) || host.respond_to?(:call)
765:               case host.is_a?(Proc) ? host.arity : host.method(:call).arity
766:               when 2
767:                 request = controller.respond_to?(:request) && controller.request
768:                 host.call(source, request)
769:               else
770:                 host.call(source)
771:               end
772:             else
773:               (host =~ /%d/) ? host % (source.hash % 4) : host
774:             end
775:           end
776:         end
compute_javascript_paths(*args) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 829
829:         def compute_javascript_paths(*args)
830:           expand_javascript_sources(*args).collect { |source| compute_public_path(source, 'javascripts', 'js', false) }
831:         end
compute_public_path(source, dir, ext = nil, include_host = true) click to toggle source

Add the the extension ext if not present. Return full URLs otherwise untouched. Prefix with /dir/ if lacking a leading /. Account for relative URL roots. Rewrite the asset path for cache-busting asset ids. Include asset host, if configured, with the correct request protocol.

     # File lib/action_view/helpers/asset_tag_helper.rb, line 737
737:         def compute_public_path(source, dir, ext = nil, include_host = true)
738:           return source if is_uri?(source)
739: 
740:           source += ".#{ext}" if rewrite_extension?(source, dir, ext)
741:           source  = "/#{dir}/#{source}" unless source[0] == //
742:           source = rewrite_asset_path(source, config.asset_path)
743: 
744:           has_request = controller.respond_to?(:request)
745:           if has_request && include_host && source !~ %{^#{controller.config.relative_url_root}/}
746:             source = "#{controller.config.relative_url_root}#{source}"
747:           end
748:           source = rewrite_host_and_protocol(source, has_request) if include_host
749: 
750:           source
751:         end
compute_stylesheet_paths(*args) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 833
833:         def compute_stylesheet_paths(*args)
834:           expand_stylesheet_sources(*args).collect { |source| compute_public_path(source, 'stylesheets', 'css', false) }
835:         end
determine_source(source, collection) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 860
860:         def determine_source(source, collection)
861:           case source
862:           when Symbol
863:             collection[source] || raise(ArgumentError, "No expansion found for #{source.inspect}")
864:           else
865:             source
866:           end
867:         end
ensure_javascript_sources!(sources) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 876
876:         def ensure_javascript_sources!(sources)
877:           sources.each do |source|
878:             asset_file_path!(path_to_javascript(source))
879:           end
880:           return sources
881:         end
ensure_stylesheet_sources!(sources) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 869
869:         def ensure_stylesheet_sources!(sources)
870:           sources.each do |source|
871:             asset_file_path!(path_to_stylesheet(source))
872:           end
873:           return sources
874:         end
expand_javascript_sources(sources, recursive = false) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 837
837:         def expand_javascript_sources(sources, recursive = false)
838:           if sources.include?(:all)
839:             all_javascript_files = (collect_asset_files(config.javascripts_dir, ('**' if recursive), '*.js') - ['application']) << 'application'
840:             ((determine_source(:defaults, @@javascript_expansions).dup & all_javascript_files) + all_javascript_files).uniq
841:           else
842:             expanded_sources = sources.collect do |source|
843:               determine_source(source, @@javascript_expansions)
844:             end.flatten
845:             expanded_sources << "application" if sources.include?(:defaults) && File.exist?(File.join(config.javascripts_dir, "application.js"))
846:             expanded_sources
847:           end
848:         end
expand_stylesheet_sources(sources, recursive) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 850
850:         def expand_stylesheet_sources(sources, recursive)
851:           if sources.first == :all
852:             collect_asset_files(config.stylesheets_dir, ('**' if recursive), '*.css')
853:           else
854:             sources.collect do |source|
855:               determine_source(source, @@stylesheet_expansions)
856:             end.flatten
857:           end
858:         end
is_uri?(path) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 753
753:         def is_uri?(path)
754:           path =~ %{^[-a-z]+://|^cid:}
755:         end
javascript_src_tag(source, options) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 821
821:         def javascript_src_tag(source, options)
822:           content_tag("script", "", { "type" => Mime::JS, "src" => path_to_javascript(source) }.merge(options))
823:         end
join_asset_file_contents(paths) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 883
883:         def join_asset_file_contents(paths)
884:           paths.collect { |path| File.read(asset_file_path!(path)) }.join("\n\n")
885:         end
rails_asset_id(source) click to toggle source

Use the RAILS_ASSET_ID environment variable or the source’s modification time as its cache-busting asset id.

     # File lib/action_view/helpers/asset_tag_helper.rb, line 783
783:         def rails_asset_id(source)
784:           if asset_id = ENV["RAILS_ASSET_ID"]
785:             asset_id
786:           else
787:             if @@cache_asset_timestamps && (asset_id = @@asset_timestamps_cache[source])
788:               asset_id
789:             else
790:               path = File.join(config.assets_dir, source)
791:               asset_id = File.exist?(path) ? File.mtime(path).to_i.to_s : ''
792: 
793:               if @@cache_asset_timestamps
794:                 @@asset_timestamps_cache_guard.synchronize do
795:                   @@asset_timestamps_cache[source] = asset_id
796:                 end
797:               end
798: 
799:               asset_id
800:             end
801:           end
802:         end
rewrite_asset_path(source, path = nil) click to toggle source

Break out the asset path rewrite in case plugins wish to put the asset id someplace other than the query string.

     # File lib/action_view/helpers/asset_tag_helper.rb, line 806
806:         def rewrite_asset_path(source, path = nil)
807:           if path && path.respond_to?(:call)
808:             return path.call(source)
809:           elsif path && path.is_a?(String)
810:             return path % [source]
811:           end
812: 
813:           asset_id = rails_asset_id(source)
814:           if asset_id.blank?
815:             source
816:           else
817:             source + "?#{asset_id}"
818:           end
819:         end
rewrite_extension?(source, dir, ext) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 720
720:         def rewrite_extension?(source, dir, ext)
721:           source_ext = File.extname(source)[1..1]
722:           ext && (source_ext.blank? || (ext != source_ext && File.exist?(File.join(config.assets_dir, dir, "#{source}.#{ext}"))))
723:         end
rewrite_host_and_protocol(source, has_request) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 725
725:         def rewrite_host_and_protocol(source, has_request)
726:           host = compute_asset_host(source)
727:           if has_request && host.present? && !is_uri?(host)
728:             host = "#{controller.request.protocol}#{host}"
729:           end
730:           "#{host}#{source}"
731:         end
stylesheet_tag(source, options) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 825
825:         def stylesheet_tag(source, options)
826:           tag("link", { "rel" => "stylesheet", "type" => Mime::CSS, "media" => "screen", "href" => html_escape(path_to_stylesheet(source)) }.merge(options), false, false)
827:         end
write_asset_file_contents(joined_asset_path, asset_paths) click to toggle source
     # File lib/action_view/helpers/asset_tag_helper.rb, line 887
887:         def write_asset_file_contents(joined_asset_path, asset_paths)
888: 
889:           FileUtils.mkdir_p(File.dirname(joined_asset_path))
890:           File.atomic_write(joined_asset_path) { |cache| cache.write(join_asset_file_contents(asset_paths)) }
891: 
892:           # Set mtime to the latest of the combined files to allow for
893:           # consistent ETag without a shared filesystem.
894:           mt = asset_paths.map { |p| File.mtime(asset_file_path(p)) }.max
895:           File.utime(mt, mt, joined_asset_path)
896:         end

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