ActionView::Helpers::AssetTagHelper

Provides methods for linking an HTML page together with other assets such as images, javascripts, stylesheets, and feeds. You can direct Rails to link to assets from a dedicated assets server by setting ActionController::Base.asset_host in your environment.rb. These methods do not verify the assets exist before linking to them.

ActionController::Base.asset_host = "http://assets.example.com"
image_tag("rails.png")  
  => <img src="http://assets.example.com/images/rails.png" alt="Rails" />
stylesheet_include_tag("application")
  => <link href="http://assets.example.com/stylesheets/application.css" media="screen" rel="Stylesheet" type="text/css" />

Methods

A

auto_discovery_link_tag

I

image_path,
image_tag

J

javascript_include_tag,
javascript_path

R

register_javascript_include_default

S

stylesheet_link_tag,
stylesheet_path

Constants

JAVASCRIPT_DEFAULT_SOURCES	=	['prototype', 'effects', 'dragdrop', 'controls'] unless const_defined?(:JAVASCRIPT_DEFAULT_SOURCES)

Class Public methods

register_javascript_include_default(*sources)

Register one or more additional JavaScript files to be included when javascript_include_tag :defaults is called. This method is only intended to be called from plugin initialization to register additional .js files that the plugin installed in public/javascripts.

Source: show

# File rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 106
def self.register_javascript_include_default(*sources)
  @@javascript_default_sources.concat(sources)
end

Instance Public methods

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

Returns a link tag that browsers and news 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.

Tag 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

auto_discovery_link_tag # =>
   <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.curenthost.com/controller/action" />
auto_discovery_link_tag(:atom) # =>
   <link rel="alternate" type="application/atom+xml" title="ATOM" href="http://www.curenthost.com/controller/action" />
auto_discovery_link_tag(:rss, {:action => "feed"}) # =>
   <link rel="alternate" type="application/rss+xml" title="RSS" href="http://www.curenthost.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.curenthost.com/controller/feed" />

Source: show

# File rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 37
def auto_discovery_link_tag(type = :rss, url_options = {}, tag_options = {})
  tag(
    "link", 
    "rel"   => tag_options[:rel] || "alternate",
    "type"  => tag_options[:type] || "application/#{type}+xml",
    "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

image_path(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. Passing a filename without an extension is deprecated.

image_path("edit.png")  # => /images/edit.png
image_path("icons/edit.png")  # => /images/icons/edit.png
image_path("/icons/edit.png")  # => /icons/edit.png

Source: show

# File rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 155
def image_path(source)
  unless (source.split("/").last || source).include?(".") || source.blank?
    ActiveSupport::Deprecation.warn(
      "You've called image_path with a source that doesn't include an extension. " +
      "In Rails 2.0, that will not result in .png automatically being appended. " +
      "So you should call image_path('#{source}.png') instead", caller
    )
  end

  compute_public_path(source, 'images', 'png')
end

image_tag(source, options = {})

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. Note that specifying a filename without the extension is now deprecated in Rails. You can add html attributes using the options. The options supports two additional keys for convienence 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.

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" />

Source: show

# File rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 185
def image_tag(source, options = {})
  options.symbolize_keys!
          
  options[:src] = image_path(source)
  options[:alt] ||= File.basename(options[:src], '.*').split('.').first.capitalize
  
  if options[:size]
    options[:width], options[:height] = options[:size].split("x") if options[:size] =~ %r{^\d+x\d+$}
    options.delete(:size)
  end

  tag("img", options)
end

javascript_include_tag(*sources)

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.

javascript_include_tag "xmlhr" # =>
  <script type="text/javascript" src="/javascripts/xmlhr.js"><%rscript>

javascript_include_tag "common.javascript", "/lsewhere/cools" # =>
  <script type="text/javascript" src="/javascripts/common.javascript"></script>
  <script type="text/javascript" src="/elsewhere/cools.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> *see below

Source: show

# File rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 84
def javascript_include_tag(*sources)
  options = sources.last.is_a?(Hash) ? sources.pop.stringify_keys : { }

  if sources.include?(:defaults) 
    sources = sources[0..(sources.index(:defaults))] + 
      @@javascript_default_sources.dup + 
      sources[(sources.index(:defaults) + 1)..sources.length]

    sources.delete(:defaults) 
    sources << "application" if defined?(RAILS_ROOT) && File.exists?("#{RAILS_ROOT}/public/javascripts/application.js") 
  end

  sources.collect do |source|
    source = javascript_path(source)        
    content_tag("script", "", { "type" => "text/javascript", "src" => source }.merge(options))
  end.join("\n")
end

javascript_path(source)

Computes the path to a javascript asset in the public javascripts directory. If the source filename has no extension, .js will be appended. Full paths from the document root will be passed through. Used internally by #javascript_include_tag to build the script path.

javascript_path "xmlhr" # => /javascripts/xmlhr.js
javascript_path "dir/xmlhr.js" # => /javascripts/dir/xmlhr.js
javascript_path "/dir/xmlhr" # => /dir/xmlhr.js

Source: show

# File rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 55
def javascript_path(source)
  compute_public_path(source, 'javascripts', 'js')        
end

stylesheet_link_tag(*sources)

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.

stylesheet_link_tag "style" # =>
  <link href="/stylesheets/style.css" media="screen" rel="Stylesheet" type="text/css" />

stylesheet_link_tag "style", :media => "all" # =>
  <link href="/stylesheets/style.css" media="all" rel="Stylesheet" type="text/css" />

stylesheet_link_tag "random.styles", "/css/stylish" # =>
  <link href="/stylesheets/random.styles" media="screen" rel="Stylesheet" type="text/css" />
  <link href="/css/stylish.css" media="screen" rel="Stylesheet" type="text/css" />

Source: show

# File rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 139
def stylesheet_link_tag(*sources)
  options = sources.last.is_a?(Hash) ? sources.pop.stringify_keys : { }
  sources.collect do |source|
    source = stylesheet_path(source)
    tag("link", { "rel" => "Stylesheet", "type" => "text/css", "media" => "screen", "href" => source }.merge(options))
  end.join("\n")
end

stylesheet_path(source)

Computes the path to a stylesheet asset in the public stylesheets directory. If the source filename has no extension, .css will be appended. Full paths from the document root will be passed through. Used internally by #stylesheet_link_tag to build the stylesheet path.

stylesheet_path "style" # => /stylesheets/style.css
stylesheet_path "dir/style.css" # => /stylesheets/dir/style.css
stylesheet_path "/dir/style.css" # => /dir/style.css

Source: show

# File rails/actionpack/lib/action_view/helpers/asset_tag_helper.rb, line 122
def stylesheet_path(source)
  compute_public_path(source, 'stylesheets', 'css')
end

Module ActionView::Helpers::AssetTagHelper