require 'action_view/helpers/asset_tag_helpers/asset_paths'
module ActionView
# = Action View Asset URL Helpers
module Helpers #:nodoc:
# This module provides methods for generating asset paths and
# urls.
#
# image_path("rails.png")
# # => "/assets/rails.png"
#
# image_url("rails.png")
# # => "http://www.example.com/assets/rails.png"
#
# === Using asset hosts
#
# By default, Rails links to these assets on the current host in the public
# folder, but you can direct Rails to link to assets from a dedicated asset
# server by setting <tt>ActionController::Base.asset_host</tt> in the application
# configuration, typically in <tt>config/environments/production.rb</tt>.
# For example, you'd define <tt>assets.example.com</tt> to be your asset
# host this way, inside the <tt>configure</tt> block of your environment-specific
# configuration files or <tt>config/application.rb</tt>:
#
# config.action_controller.asset_host = "assets.example.com"
#
# Helpers take that into account:
#
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
# Browsers typically open at most two simultaneous connections to a single
# host, which means your assets often have to wait for other assets to finish
# downloading. You can alleviate this by using a <tt>%d</tt> wildcard in the
# +asset_host+. For example, "assets%d.example.com". If that wildcard is
# present Rails distributes asset requests among the corresponding four hosts
# "assets0.example.com", ..., "assets3.example.com". With this trick browsers
# will open eight simultaneous connections rather than two.
#
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets0.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets2.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
# To do this, you can either setup four actual hosts, or you can use wildcard
# DNS to CNAME the wildcard to a single asset host. You can read more about
# setting up your DNS CNAME records from your ISP.
#
# Note: This is purely a browser performance optimization and is not meant
# for server load balancing. See http://www.die.net/musings/page_load_time/
# for background.
#
# Alternatively, you can exert more control over the asset host by setting
# +asset_host+ to a proc like this:
#
# ActionController::Base.asset_host = Proc.new { |source|
# "http://assets#{Digest::MD5.hexdigest(source).to_i(16) % 2 + 1}.example.com"
# }
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets1.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets2.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
# The example above generates "http://assets1.example.com" and
# "http://assets2.example.com". This option is useful for example if
# you need fewer/more than four hosts, custom host names, etc.
#
# As you see the proc takes a +source+ parameter. That's a string with the
# absolute path of the asset, for example "/assets/rails.png".
#
# ActionController::Base.asset_host = Proc.new { |source|
# if source.ends_with?('.css')
# "http://stylesheets.example.com"
# else
# "http://assets.example.com"
# end
# }
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://stylesheets.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
# Alternatively you may ask for a second parameter +request+. That one is
# particularly useful for serving assets from an SSL-protected page. The
# example proc below disables asset hosting for HTTPS connections, while
# still sending assets for plain HTTP requests from asset hosts. If you don't
# have SSL certificates for each of the asset hosts this technique allows you
# to avoid warnings in the client about mixed media.
#
# config.action_controller.asset_host = Proc.new { |source, request|
# if request.ssl?
# "#{request.protocol}#{request.host_with_port}"
# else
# "#{request.protocol}assets.example.com"
# end
# }
#
# You can also implement a custom asset host object that responds to +call+
# and takes either one or two parameters just like the proc.
#
# config.action_controller.asset_host = AssetHostingWithMinimumSsl.new(
# "http://asset%d.example.com", "https://asset1.example.com"
# )
#
# === Customizing the asset path
#
# By default, Rails appends asset's timestamps to all asset paths. This allows
# you to set a cache-expiration date for the asset far into the future, but
# still be able to instantly invalidate it by simply updating the file (and
# hence updating the timestamp, which then updates the URL as the timestamp
# is part of that, which in turn busts the cache).
#
# It's the responsibility of the web server you use to set the far-future
# expiration date on cache assets that you need to take advantage of this
# feature. Here's an example for Apache:
#
# # Asset Expiration
# ExpiresActive On
# <FilesMatch "\.(ico|gif|jpe?g|png|js|css)$">
# ExpiresDefault "access plus 1 year"
# </FilesMatch>
#
# Also note that in order for this to work, all your application servers must
# return the same timestamps. This means that they must have their clocks
# synchronized. If one of them drifts out of sync, you'll see different
# timestamps at random and the cache won't work. In that case the browser
# will request the same assets over and over again even thought they didn't
# change. You can use something like Live HTTP Headers for Firefox to verify
# that the cache is indeed working.
#
# This strategy works well enough for most server setups and requires the
# least configuration, but if you deploy several application servers at
# different times - say to handle a temporary spike in load - then the
# asset time stamps will be out of sync. In a setup like this you may want
# to set the way that asset paths are generated yourself.
#
# Altering the asset paths that Rails generates can be done in two ways.
# The easiest is to define the RAILS_ASSET_ID environment variable. The
# contents of this variable will always be used in preference to
# calculated timestamps. A more complex but flexible way is to set
# <tt>ActionController::Base.config.asset_path</tt> to a proc
# that takes the unmodified asset path and returns the path needed for
# your asset caching to work. Typically you'd do something like this in
# <tt>config/environments/production.rb</tt>:
#
# # Normally you'd calculate RELEASE_NUMBER at startup.
# RELEASE_NUMBER = 12345
# config.action_controller.asset_path = proc { |asset_path|
# "/release-#{RELEASE_NUMBER}#{asset_path}"
# }
#
# This example would cause the following behavior on all servers no
# matter when they were deployed:
#
# image_tag("rails.png")
# # => <img alt="Rails" src="/release-12345/images/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="/release-12345/stylesheets/application.css?1232285206" media="screen" rel="stylesheet" />
#
# Changing the asset_path does require that your web servers have
# knowledge of the asset template paths that you rewrite to so it's not
# suitable for out-of-the-box use. To use the example given above you
# could use something like this in your Apache VirtualHost configuration:
#
# <LocationMatch "^/release-\d+/(images|javascripts|stylesheets)/.*$">
# # Some browsers still send conditional-GET requests if there's a
# # Last-Modified header or an ETag header even if they haven't
# # reached the expiry date sent in the Expires header.
# Header unset Last-Modified
# Header unset ETag
# FileETag None
#
# # Assets requested using a cache-busting filename should be served
# # only once and then cached for a really long time. The HTTP/1.1
# # spec frowns on hugely-long expiration times though and suggests
# # that assets which never expire be served with an expiration date
# # 1 year from access.
# ExpiresActive On
# ExpiresDefault "access plus 1 year"
# </LocationMatch>
#
# # We use cached-busting location names with the far-future expires
# # headers to ensure that if a file does change it can force a new
# # request. The actual asset filenames are still the same though so we
# # need to rewrite the location from the cache-busting location to the
# # real asset location so that we can serve it.
# RewriteEngine On
# RewriteRule ^/release-\d+/(images|javascripts|stylesheets)/(.*)$ /$1/$2 [L]
#
module AssetUrlHelper
# Computes the path to a javascript asset in the public javascripts directory.
# If the +source+ filename has no extension, .js will be appended (except for explicit URIs)
# 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
# javascript_path "http://www.example.com/js/xmlhr" # => http://www.example.com/js/xmlhr
# javascript_path "http://www.example.com/js/xmlhr.js" # => http://www.example.com/js/xmlhr.js
def javascript_path(source)
asset_paths.compute_public_path(source, 'javascripts', :ext => 'js')
end
alias_method :path_to_javascript, :javascript_path # aliased to avoid conflicts with a javascript_path named route
# Computes the full URL to a javascript asset in the public javascripts directory.
# This will use +javascript_path+ internally, so most of their behaviors will be the same.
def javascript_url(source)
URI.join(current_host, path_to_javascript(source)).to_s
end
alias_method :url_to_javascript, :javascript_url # aliased to avoid conflicts with a javascript_url named route
# Computes the path to a stylesheet asset in the public stylesheets directory.
# If the +source+ filename has no extension, <tt>.css</tt> will be appended (except for explicit URIs).
# 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
# stylesheet_path "http://www.example.com/css/style" # => http://www.example.com/css/style
# stylesheet_path "http://www.example.com/css/style.css" # => http://www.example.com/css/style.css
def stylesheet_path(source)
asset_paths.compute_public_path(source, 'stylesheets', :ext => 'css', :protocol => :request)
end
alias_method :path_to_stylesheet, :stylesheet_path # aliased to avoid conflicts with a stylesheet_path named route
# Computes the full URL to a stylesheet asset in the public stylesheets directory.
# This will use +stylesheet_path+ internally, so most of their behaviors will be the same.
def stylesheet_url(source)
URI.join(current_host, path_to_stylesheet(source)).to_s
end
alias_method :url_to_stylesheet, :stylesheet_url # aliased to avoid conflicts with a stylesheet_url named route
# Computes the path to an image asset.
# Full paths from the document root will be passed through.
# Used internally by +image_tag+ to build the image path:
#
# image_path("edit") # => "/assets/edit"
# image_path("edit.png") # => "/assets/edit.png"
# image_path("icons/edit.png") # => "/assets/icons/edit.png"
# image_path("/icons/edit.png") # => "/icons/edit.png"
# image_path("http://www.example.com/img/edit.png") # => "http://www.example.com/img/edit.png"
#
# If you have images as application resources this method may conflict with their named routes.
# The alias +path_to_image+ is provided to avoid that. Rails uses the alias internally, and
# plugin authors are encouraged to do so.
def image_path(source)
source.present? ? asset_paths.compute_public_path(source, 'images') : ""
end
alias_method :path_to_image, :image_path # aliased to avoid conflicts with an image_path named route
# Computes the full URL to an image asset.
# This will use +image_path+ internally, so most of their behaviors will be the same.
def image_url(source)
URI.join(current_host, path_to_image(source)).to_s
end
alias_method :url_to_image, :image_url # aliased to avoid conflicts with an image_url named route
# Computes the path to a video asset in the public videos directory.
# Full paths from the document root will be passed through.
# Used internally by +video_tag+ to build the video path.
#
# video_path("hd") # => /videos/hd
# video_path("hd.avi") # => /videos/hd.avi
# video_path("trailers/hd.avi") # => /videos/trailers/hd.avi
# video_path("/trailers/hd.avi") # => /trailers/hd.avi
# video_path("http://www.example.com/vid/hd.avi") # => http://www.example.com/vid/hd.avi
def video_path(source)
asset_paths.compute_public_path(source, 'videos')
end
alias_method :path_to_video, :video_path # aliased to avoid conflicts with a video_path named route
# Computes the full URL to a video asset in the public videos directory.
# This will use +video_path+ internally, so most of their behaviors will be the same.
def video_url(source)
URI.join(current_host, path_to_video(source)).to_s
end
alias_method :url_to_video, :video_url # aliased to avoid conflicts with an video_url named route
# Computes the path to an audio asset in the public audios directory.
# Full paths from the document root will be passed through.
# Used internally by +audio_tag+ to build the audio path.
#
# audio_path("horse") # => /audios/horse
# audio_path("horse.wav") # => /audios/horse.wav
# audio_path("sounds/horse.wav") # => /audios/sounds/horse.wav
# audio_path("/sounds/horse.wav") # => /sounds/horse.wav
# audio_path("http://www.example.com/sounds/horse.wav") # => http://www.example.com/sounds/horse.wav
def audio_path(source)
asset_paths.compute_public_path(source, 'audios')
end
alias_method :path_to_audio, :audio_path # aliased to avoid conflicts with an audio_path named route
# Computes the full URL to an audio asset in the public audios directory.
# This will use +audio_path+ internally, so most of their behaviors will be the same.
def audio_url(source)
URI.join(current_host, path_to_audio(source)).to_s
end
alias_method :url_to_audio, :audio_url # aliased to avoid conflicts with an audio_url named route
# Computes the path to a font asset.
# Full paths from the document root will be passed through.
#
# font_path("font") # => /assets/font
# font_path("font.ttf") # => /assets/font.ttf
# font_path("dir/font.ttf") # => /assets/dir/font.ttf
# font_path("/dir/font.ttf") # => /dir/font.ttf
# font_path("http://www.example.com/dir/font.ttf") # => http://www.example.com/dir/font.ttf
def font_path(source)
asset_paths.compute_public_path(source, 'fonts')
end
alias_method :path_to_font, :font_path # aliased to avoid conflicts with an font_path named route
# Computes the full URL to a font asset.
# This will use +font_path+ internally, so most of their behaviors will be the same.
def font_url(source)
URI.join(current_host, path_to_font(source)).to_s
end
alias_method :url_to_font, :font_url # aliased to avoid conflicts with an font_url named route
private
def asset_paths
@asset_paths ||= AssetTagHelper::AssetPaths.new(config, controller)
end
def current_host
url_for(:only_path => false)
end
end
end
end
