module 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="/assets/rails.png" /> stylesheet_link_tag("application") # => <link href="/assets/application.css?body=1" media="screen" rel="stylesheet" />
Public Instance Methods
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>
# File lib/action_view/helpers/asset_tag_helper.rb, line 327 def audio_tag(*sources) multiple_sources_tag_builder("audio", sources) 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 thetype
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" />
# File lib/action_view/helpers/asset_tag_helper.rb, line 149 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] || Template::Types[type].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 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" />
# File lib/action_view/helpers/asset_tag_helper.rb, line 190 def favicon_link_tag(source = "favicon.ico", options = {}) tag("link", { rel: "shortcut icon", type: "image/x-icon", href: path_to_image(source, skip_pipeline: options.delete(:skip_pipeline)) }.merge!(options.symbolize_keys)) 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
# File lib/action_view/helpers/asset_tag_helper.rb, line 259 def image_alt(src) File.basename(src, ".*".freeze).sub(/-[[:xdigit:]]{32,64}\z/, "".freeze).tr("-_".freeze, " ".freeze).capitalize 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 thesource
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" /> image_tag("/icons/icon.gif", data: { title: 'Rails Application' }) # => <img data-title="Rails Application" src="/icons/icon.gif" />
# File lib/action_view/helpers/asset_tag_helper.rb, line 228 def image_tag(source, options = {}) options = options.symbolize_keys check_for_image_tag_errors(options) src = options[:src] = path_to_image(source, skip_pipeline: options.delete(:skip_pipeline)) unless src.start_with?("cid:") || src.start_with?("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 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.
Options¶ ↑
When the last parameter is a hash you can add HTML attributes using that parameter. The following options are supported:
-
:extname
- Append an extension to the generated url unless the extension already exists. This only applies for relative urls. -
:protocol
- Sets the protocol of the generated url, this option only applies when a relative url andhost
options are provided. -
:host
- When a relative url is provided the host is added to the that path. -
:skip_pipeline
- This option is used to bypass the asset pipeline when it is set to true.
Examples¶ ↑
javascript_include_tag "xmlhr" # => <script src="/assets/xmlhr.debug-1284139606.js"></script> javascript_include_tag "xmlhr", host: "localhost", protocol: "https" # => <script src="https://localhost/assets/xmlhr.debug-1284139606.js"></script> javascript_include_tag "template.jst", extname: false # => <script src="/assets/template.debug-1284139606.jst"></script> javascript_include_tag "xmlhr.js" # => <script src="/assets/xmlhr.debug-1284139606.js"></script> javascript_include_tag "common.javascript", "/elsewhere/cools" # => <script src="/assets/common.javascript.debug-1284139606.js"></script> # <script src="/elsewhere/cools.debug-1284139606.js"></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>
# File lib/action_view/helpers/asset_tag_helper.rb, line 75 def javascript_include_tag(*sources) options = sources.extract_options!.stringify_keys path_options = options.extract!("protocol", "extname", "host", "skip_pipeline").symbolize_keys sources.uniq.map { |source| tag_options = { "src" => path_to_javascript(source, path_options) }.merge!(options) content_tag("script".freeze, "", 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" />
# File lib/action_view/helpers/asset_tag_helper.rb, line 111 def stylesheet_link_tag(*sources) options = sources.extract_options!.stringify_keys path_options = options.extract!("protocol", "host", "skip_pipeline").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 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 thesrc
ofimage_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. -
:poster_skip_pipeline
will bypass the asset pipeline when using the:poster
option instead using an asset in the public folder.
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, preload: 'none') # => <video preload="none" 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("trailer.m4v", size: "16x10", poster: "screenshot.png", poster_skip_pipeline: true) # => <video src="/videos/trailer.m4v" width="16" height="10" poster="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>
# File lib/action_view/helpers/asset_tag_helper.rb, line 305 def video_tag(*sources) options = sources.extract_options!.symbolize_keys public_poster_folder = options.delete(:poster_skip_pipeline) sources << options multiple_sources_tag_builder("video", sources) do |tag_options| tag_options[:poster] = path_to_image(tag_options[:poster], skip_pipeline: public_poster_folder) if tag_options[:poster] tag_options[:width], tag_options[:height] = extract_dimensions(tag_options.delete(:size)) if tag_options[:size] end end
Private Instance Methods
# File lib/action_view/helpers/asset_tag_helper.rb, line 358 def check_for_image_tag_errors(options) if options[:size] && (options[:height] || options[:width]) raise ArgumentError, "Cannot pass a :size option with a :height or :width option" end end
# File lib/action_view/helpers/asset_tag_helper.rb, line 349 def extract_dimensions(size) size = size.to_s if /\A\d+x\d+\z/.match?(size) size.split("x") elsif /\A\d+\z/.match?(size) [size, size] end end
# File lib/action_view/helpers/asset_tag_helper.rb, line 332 def multiple_sources_tag_builder(type, sources) options = sources.extract_options!.symbolize_keys skip_pipeline = options.delete(:skip_pipeline) sources.flatten! yield options if block_given? if sources.size > 1 content_tag(type, options) do safe_join sources.map { |source| tag("source", src: send("path_to_#{type}", source, skip_pipeline: skip_pipeline)) } end else options[:src] = send("path_to_#{type}", sources.first, skip_pipeline: skip_pipeline) content_tag(type, nil, options) end end