module ActionView::Helpers::AssetTagHelper

Included modules:: ActionView::Helpers::AssetUrlHelper, ActionView::Helpers::TagHelper

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="/assets/rails.png" />
stylesheet_link_tag("application")
# => <link href="/assets/application.css?body=1" media="screen" rel="stylesheet" />

Public Instance Methods

audio_tag(*sources) Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 299
def audio_tag(*sources)
  multiple_sources_tag('audio', sources)
end

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

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

auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {}) Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 131
def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})
  if !(type == :rss || type == :atom) && tag_options[:type].blank?
    raise ArgumentError.new("You should pass :type tag_option key explicitly, because you have passed #{type} type other than :rss or :atom.")
  end

  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

Returns a link tag that browsers and feed 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.rss" />

favicon_link_tag(source='favicon.ico', options={}) Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 172
def favicon_link_tag(source='favicon.ico', options={})
  tag('link', {
    :rel  => 'shortcut icon',
    :type => 'image/x-icon',
    :href => path_to_image(source)
  }.merge!(options.symbolize_keys))
end

Returns a link tag for a favicon managed by the asset pipeline.

If a page has no link like the one generated by this helper, browsers ask for /favicon.ico automatically, and cache the file if the request succeeds. If the favicon changes it is hard to get it updated.

To have better control applications may let the asset pipeline manage their favicon storing the file under app/assets/images, and using this helper to generate its corresponding link tag.

The helper gets the name of the favicon file as first argument, which defaults to “favicon.ico”, and also supports :rel and :type options to override their defaults, “shortcut icon” and “image/x-icon” respectively:

favicon_link_tag
# => <link href="/assets/favicon.ico" rel="shortcut icon" type="image/x-icon" />

favicon_link_tag 'myicon.ico'
# => <link href="/assets/myicon.ico" rel="shortcut icon" type="image/x-icon" />

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 iOS device. The following call would generate such a tag:

favicon_link_tag 'mb-icon.png', rel: 'apple-touch-icon', type: 'image/png'
# => <link href="/assets/mb-icon.png" rel="apple-touch-icon" type="image/png" />

image_alt(src) Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 238
def image_alt(src)
  File.basename(src, '.*').sub(/-[[:xdigit:]]{32,64}\z/, '').tr('-_', ' ').capitalize
end

Returns a string suitable for an HTML image tag alt attribute. The src argument is meant to be an image file path. The method removes the basename of the file path and the digest, if any. It also removes hyphens and underscores from file names and replaces them with spaces, returning a space-separated, titleized string.

Examples

image_alt('rails.png')
# => Rails

image_alt('hyphenated-file-name.png')
# => Hyphenated file name

image_alt('underscored_file_name.png')
# => Underscored file name

image_tag(source, options={}) Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 208
def image_tag(source, options={})
  options = options.symbolize_keys

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

  unless src =~ /^(?:cid|data):/ || src.blank?
    options[:alt] = options.fetch(:alt){ image_alt(src) }
  end

  options[:width], options[:height] = extract_dimensions(options.delete(:size)) if options[:size]
  tag("img", options)
end

Returns an HTML image tag for the source. The source can be a full path or a file.

Options

You can add HTML attributes using the options. The options supports two 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}” or “{Number}”, so “30x45” becomes width=“30” and height=“45”, and “50” becomes width=“50” and height=“50”. :size will be ignored if the value is not in the correct format.

Examples

image_tag("icon")
# => <img alt="Icon" src="/assets/icon" />
image_tag("icon.png")
# => <img alt="Icon" src="/assets/icon.png" />
image_tag("icon.png", size: "16x10", alt: "Edit Entry")
# => <img src="/assets/icon.png" width="16" height="10" alt="Edit Entry" />
image_tag("/icons/icon.gif", size: "16")
# => <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" />

javascript_include_tag(*sources) Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 56
def javascript_include_tag(*sources)
  options = sources.extract_options!.stringify_keys
  path_options = options.extract!('protocol', 'extname').symbolize_keys
  sources.uniq.map { |source|
    tag_options = {
      "src" => path_to_javascript(source, path_options)
    }.merge!(options)
    content_tag(:script, "", tag_options)
  }.join("\n").html_safe
end

Returns an HTML script tag for each of the sources provided.

Sources may be paths to JavaScript files. Relative paths are assumed to be relative to assets/javascripts, full paths are assumed to be relative to the document root. Relative paths are idiomatic, use absolute paths only when needed.

When passing paths, the “.js” extension is optional. If you do not want “.js” appended to the path extname: false can be set on the options.

You can modify the HTML attributes of the script tag by passing a hash as the last argument.

When the Asset Pipeline is enabled, you can pass the name of your manifest as source, and include other JavaScript or CoffeeScript files inside the manifest.

javascript_include_tag "xmlhr"
# => <script src="/assets/xmlhr.js?1284139606"></script>

javascript_include_tag "template.jst", extname: false
# => <script src="/assets/template.jst?1284139606"></script>

javascript_include_tag "xmlhr.js"
# => <script src="/assets/xmlhr.js?1284139606"></script>

javascript_include_tag "common.javascript", "/elsewhere/cools"
# => <script src="/assets/common.javascript?1284139606"></script>
#    <script src="/elsewhere/cools.js?1423139606"></script>

javascript_include_tag "http://www.example.com/xmlhr"
# => <script src="http://www.example.com/xmlhr"></script>

javascript_include_tag "http://www.example.com/xmlhr.js"
# => <script src="http://www.example.com/xmlhr.js"></script>

stylesheet_link_tag(*sources) Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 92
def stylesheet_link_tag(*sources)
  options = sources.extract_options!.stringify_keys
  path_options = options.extract!('protocol').symbolize_keys

  sources.uniq.map { |source|
    tag_options = {
      "rel" => "stylesheet",
      "media" => "screen",
      "href" => path_to_stylesheet(source, path_options)
    }.merge!(options)
    tag(:link, tag_options)
  }.join("\n").html_safe
end

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. For historical reasons, the 'media' attribute will always be present and defaults to “screen”, so you must explicitly set it to “all” for the stylesheet(s) to apply to all media types.

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

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

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

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

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

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

video_tag(*sources) Show source

# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 280
def video_tag(*sources)
  multiple_sources_tag('video', sources) do |options|
    options[:poster] = path_to_image(options[:poster]) if options[:poster]
    options[:width], options[:height] = extract_dimensions(options.delete(:size)) if options[:size]
  end
end

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}” or “{Number}”, so “30x45” becomes width=“30” and height=“45”, and “50” becomes width=“50” and height=“50”. :size will be ignored if the value is not in the correct format.

Examples

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