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("quails.png") # => <img src="/assets/quails.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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 352 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, Atom, or JSON feed. The type
can be :rss
(default), :atom
, or :json
. 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(:json) # => <link rel="alternate" type="application/json" title="JSON" 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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 153 def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {}) if !(type == :rss || type == :atom || type == :json) && tag_options[:type].blank? raise ArgumentError.new("You should pass :type tag_option key explicitly, because you have passed #{type} type other than :rss, :atom, or :json.") 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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 194 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('quails.png') # => Quails image_alt('hyphenated-file-name.png') # => Hyphenated file name image_alt('underscored_file_name.png') # => Underscored file name
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 282 def image_alt(src) ActiveSupport::Deprecation.warn("image_alt is deprecated and will be removed from Quails 6.0. You must explicitly set alt text on images.") 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, a file or an Active Storage attachment.
Options¶ ↑
You can add HTML
attributes using the options
. The options
supports additional keys for convenience and conformance:
-
: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. -
:srcset
- If supplied as a hash or array of[source, descriptor]
pairs, each image path will be expanded before the list is formatted as a string.
Examples¶ ↑
Assets (images that are part of your app):
image_tag("icon") # => <img src="/assets/icon" /> image_tag("icon.png") # => <img 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" /> image_tag("/icons/icon.gif", height: '32', width: '32') # => <img height="32" src="/icons/icon.gif" width="32" /> image_tag("/icons/icon.gif", class: "menu_icon") # => <img class="menu_icon" src="/icons/icon.gif" /> image_tag("/icons/icon.gif", data: { title: 'Quails Application' }) # => <img data-title="Quails Application" src="/icons/icon.gif" /> image_tag("icon.png", srcset: { "icon_2x.png" => "2x", "icon_4x.png" => "4x" }) # => <img src="/assets/icon.png" srcset="/assets/icon_2x.png 2x, /assets/icon_4x.png 4x"> image_tag("pic.jpg", srcset: [["pic_1024.jpg", "1024w"], ["pic_1980.jpg", "1980w"]], sizes: "100vw") # => <img src="/assets/pic.jpg" srcset="/assets/pic_1024.jpg 1024w, /assets/pic_1980.jpg 1980w" sizes="100vw">
Active Storage (images that are uploaded by the users of your app):
image_tag(user.avatar) # => <img src="/quails/active_storage/blobs/.../tiger.jpg" /> image_tag(user.avatar.variant(resize: "100x100")) # => <img src="/quails/active_storage/variants/.../tiger.jpg" /> image_tag(user.avatar.variant(resize: "100x100"), size: '100') # => <img width="100" height="100" src="/quails/active_storage/variants/.../tiger.jpg" />
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 247 def image_tag(source, options = {}) options = options.symbolize_keys check_for_image_tag_errors(options) skip_pipeline = options.delete(:skip_pipeline) options[:src] = resolve_image_source(source, skip_pipeline) if options[:srcset] && !options[:srcset].is_a?(String) options[:srcset] = options[:srcset].map do |src_path, size| src_path = path_to_image(src_path, skip_pipeline: skip_pipeline) "#{src_path} #{size}" end.join(", ") 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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 77 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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 113 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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 330 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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 393 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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 384 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 actionview/lib/action_view/helpers/asset_tag_helper.rb, line 357 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
# File actionview/lib/action_view/helpers/asset_tag_helper.rb, line 374 def resolve_image_source(source, skip_pipeline) if source.is_a?(Symbol) || source.is_a?(String) path_to_image(source, skip_pipeline: skip_pipeline) else polymorphic_url(source) end rescue NoMethodError => e raise ArgumentError, "Can't resolve image into URL: #{e}" end