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Module: ActionView::Helpers::AssetTagHelper

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In:
::ActionView::Base, ::ActionView::Helpers, ::ActionView::TestCase, ::ActionView::TestCase::Behavior
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ::ActiveSupport::Concern
Instance Chain:
self, TagHelper, CaptureHelper, AssetUrlHelper
Defined in: actionview/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="/assets/rails.png" />
stylesheet_link_tag("application")
# => <link href="/assets/application.css?body=1" media="screen" rel="stylesheet" />

Constant Summary

AssetUrlHelper - Included

ASSET_EXTENSIONS, ASSET_PUBLIC_DIRECTORIES, URI_REGEXP

TagHelper - Included

BOOLEAN_ATTRIBUTES, PRE_CONTENT_STRINGS, TAG_PREFIXES

Class Method Summary

::ActiveSupport::Concern - Extended

append_features, class_methods, included

Instance Method Summary

TagHelper - Included

#cdata_section

Returns a CDATA section with the given content.
#content_tag

Returns an HTML block tag of type name surrounding the content.
#escape_once

Returns an escaped version of html without affecting existing escaped entities.
#tag

Returns an empty HTML tag of type name which by default is XHTML compliant.

CaptureHelper - Included

#capture

The capture method allows you to extract part of a template into a variable.
#content_for

Calling content_for stores a block of markup in an identifier for later use.
#content_for?

content_for? checks whether any content has been captured yet using content_for.
#provide

The same as content_for but when used with streaming flushes straight back to the layout.

AssetUrlHelper - Included

#asset_path

Computes the path to asset in public directory.
#asset_url

Computes the full URL to an asset in the public directory.
#audio_path

Computes the path to an audio asset in the public audios directory.
#audio_url

Computes the full URL to an audio asset in the public audios directory.
#compute_asset_extname

Compute extname to append to asset path.
#compute_asset_host

Pick an asset host for this source.
#compute_asset_path

Computes asset path to public directory.
#font_path

Computes the path to a font asset.
#font_url

Computes the full URL to a font asset.
#image_path

Computes the path to an image asset.
#image_url

Computes the full URL to an image asset.
#javascript_path

Computes the path to a JavaScript asset in the public javascripts directory.
#javascript_url

Computes the full URL to a JavaScript asset in the public javascripts directory.
#path_to_asset

Alias for AssetUrlHelper#asset_path.
#path_to_audio

Alias for AssetUrlHelper#audio_path.
#path_to_font

Alias for AssetUrlHelper#font_path.
#path_to_image

Alias for AssetUrlHelper#image_path.
#path_to_javascript

Alias for AssetUrlHelper#javascript_path.
#path_to_stylesheet

Alias for AssetUrlHelper#stylesheet_path.
#path_to_video

Alias for AssetUrlHelper#video_path.
#stylesheet_path

Computes the path to a stylesheet asset in the public stylesheets directory.
#stylesheet_url

Computes the full URL to a stylesheet asset in the public stylesheets directory.
#url_to_asset

Alias for AssetUrlHelper#asset_url.
#url_to_audio

Alias for AssetUrlHelper#audio_url.
#url_to_font

Alias for AssetUrlHelper#font_url.
#url_to_image

Alias for AssetUrlHelper#image_url.
#url_to_javascript

Alias for AssetUrlHelper#javascript_url.
#url_to_stylesheet

Alias for AssetUrlHelper#stylesheet_url.
#url_to_video

Alias for AssetUrlHelper#video_url.
#video_path

Computes the path to a video asset in the public videos directory.
#video_url

Computes the full URL to a video asset in the public videos directory.

Instance Method Details

#audio_tag(*sources)

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>
[ GitHub ] 

  


# File 'actionview/lib/action_view/helpers/asset_tag_helper.rb', line 299



def audio_tag(*sources)
  multiple_sources_tag('audio', sources)
end


  












  

    #image_alt(src)  
  



  

    

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


  



  [ GitHub ]


  

  


# 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


  








  

    #image_tag(source, options = {})  
  



  

    

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 “WidthxHeight” 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" />


  



  [ GitHub ]


  

  


# 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


  








  

    #javascript_include_tag(*sources)  
  



  

    

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>


  



  [ GitHub ]


  

  


# 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


  










  

    #video_tag(*sources)  
  



  

    

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” 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>


  



  [ GitHub ]


  

  


# 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