actionview/lib/action_view/helpers/asset_url_helper.rb
# frozen_string_literal: true
require "zlib"
module ActionView
module Helpers # :nodoc:
# = Action View Asset URL \Helpers
#
# 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 src="http://assets.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets.example.com/assets/application.css" rel="stylesheet" />
#
# Browsers open a limited number of simultaneous connections to a single
# host. The exact number varies by browser and version. This limit may cause
# some asset downloads to wait for previous assets to finish before they can
# begin. You can use the <tt>%d</tt> wildcard in the +asset_host+ to
# distribute the requests over four hosts. For example,
# <tt>assets%d.example.com</tt> will spread the asset requests over
# "assets0.example.com", ..., "assets3.example.com".
#
# image_tag("rails.png")
# # => <img src="http://assets0.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets2.example.com/assets/application.css" rel="stylesheet" />
#
# This may improve the asset loading performance of your application.
# It is also possible the combination of additional connection overhead
# (DNS, SSL) and the overall browser connection limits may result in this
# solution being slower. You should be sure to measure your actual
# performance across targeted browsers both before and after this change.
#
# To implement the corresponding hosts you can either set up four actual
# hosts or 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 https://www.die.net/musings/page_load_time/
# for background and https://www.browserscope.org/?category=network for
# connection limit data.
#
# 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#{OpenSSL::Digest::SHA256.hexdigest(source).to_i(16) % 2 + 1}.example.com"
# }
# image_tag("rails.png")
# # => <img src="http://assets1.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets2.example.com/assets/application.css" 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.end_with?('.css')
# "http://stylesheets.example.com"
# else
# "http://assets.example.com"
# end
# }
# image_tag("rails.png")
# # => <img src="http://assets.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://stylesheets.example.com/assets/application.css" 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.
# Note that the +request+ parameter might not be supplied, e.g. when the assets
# are precompiled with the command <tt>bin/rails assets:precompile</tt>. Make sure to use a
# +Proc+ instead of a lambda, since a +Proc+ allows missing parameters and sets them
# to +nil+.
#
# config.action_controller.asset_host = Proc.new { |source, request|
# if request && 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"
# )
#
module AssetUrlHelper
URI_REGEXP = %r{^[-a-z]+://|^(?:cid|data):|^//}i
# This is the entry point for all assets.
# When using an asset pipeline gem (e.g. propshaft or sprockets-rails), the
# behavior is "enhanced". You can bypass the asset pipeline by passing in
# <tt>skip_pipeline: true</tt> to the options.
#
# All other asset *_path helpers delegate through this method.
#
# === With the asset pipeline
#
# All options passed to +asset_path+ will be passed to +compute_asset_path+
# which is implemented by asset pipeline gems.
#
# asset_path("application.js") # => "/assets/application-60aa4fdc5cea14baf5400fba1abf4f2a46a5166bad4772b1effe341570f07de9.js"
# asset_path('application.js', host: 'example.com') # => "//example.com/assets/application.js"
# asset_path("application.js", host: 'example.com', protocol: 'https') # => "https://example.com/assets/application.js"
#
# === Without the asset pipeline (<tt>skip_pipeline: true</tt>)
#
# Accepts a <tt>type</tt> option that can specify the asset's extension. No error
# checking is done to verify the source passed into +asset_path+ is valid
# and that the file exists on disk.
#
# asset_path("application.js", skip_pipeline: true) # => "application.js"
# asset_path("filedoesnotexist.png", skip_pipeline: true) # => "filedoesnotexist.png"
# asset_path("application", type: :javascript, skip_pipeline: true) # => "/javascripts/application.js"
# asset_path("application", type: :stylesheet, skip_pipeline: true) # => "/stylesheets/application.css"
#
# === Options applying to all assets
#
# Below lists scenarios that apply to +asset_path+ whether or not you're
# using the asset pipeline.
#
# - All fully qualified URLs are returned immediately. This bypasses the
# asset pipeline and all other behavior described.
#
# asset_path("http://www.example.com/js/xmlhr.js") # => "http://www.example.com/js/xmlhr.js"
#
# - All assets that begin with a forward slash are assumed to be full
# URLs and will not be expanded. This will bypass the asset pipeline.
#
# asset_path("/foo.png") # => "/foo.png"
#
# - All blank strings will be returned immediately. This bypasses the
# asset pipeline and all other behavior described.
#
# asset_path("") # => ""
#
# - If <tt>config.relative_url_root</tt> is specified, all assets will have that
# root prepended.
#
# Rails.application.config.relative_url_root = "bar"
# asset_path("foo.js", skip_pipeline: true) # => "bar/foo.js"
#
# - A different asset host can be specified via <tt>config.action_controller.asset_host</tt>
# this is commonly used in conjunction with a CDN.
#
# Rails.application.config.action_controller.asset_host = "assets.example.com"
# asset_path("foo.js", skip_pipeline: true) # => "http://assets.example.com/foo.js"
#
# - An extension name can be specified manually with <tt>extname</tt>.
#
# asset_path("foo", skip_pipeline: true, extname: ".js") # => "/foo.js"
# asset_path("foo.css", skip_pipeline: true, extname: ".js") # => "/foo.css.js"
def asset_path(source, options = {})
raise ArgumentError, "nil is not a valid asset source" if source.nil?
source = source.to_s
return "" if source.blank?
return source if URI_REGEXP.match?(source)
tail, source = source[/([?#].+)$/], source.sub(/([?#].+)$/, "")
if extname = compute_asset_extname(source, options)
source = "#{source}#{extname}"
end
unless source.start_with?(?/)
if options[:skip_pipeline]
source = public_compute_asset_path(source, options)
else
source = compute_asset_path(source, options)
end
end
relative_url_root = defined?(config.relative_url_root) && config.relative_url_root
if relative_url_root
source = File.join(relative_url_root, source) unless source.start_with?("#{relative_url_root}/")
end
if host = compute_asset_host(source, options)
source = File.join(host, source)
end
"#{source}#{tail}"
end
alias_method :path_to_asset, :asset_path # aliased to avoid conflicts with an asset_path named route
# Computes the full URL to an asset in the public directory. This
# will use +asset_path+ internally, so most of their behaviors
# will be the same. If +:host+ options is set, it overwrites global
# +config.action_controller.asset_host+ setting.
#
# All other options provided are forwarded to +asset_path+ call.
#
# asset_url "application.js" # => http://example.com/assets/application.js
# asset_url "application.js", host: "http://cdn.example.com" # => http://cdn.example.com/assets/application.js
#
def asset_url(source, options = {})
path_to_asset(source, options.merge(protocol: :request))
end
alias_method :url_to_asset, :asset_url # aliased to avoid conflicts with an asset_url named route
ASSET_EXTENSIONS = {
javascript: ".js",
stylesheet: ".css"
}
# Compute extname to append to asset path. Returns +nil+ if
# nothing should be added.
def compute_asset_extname(source, options = {})
return if options[:extname] == false
extname = options[:extname] || ASSET_EXTENSIONS[options[:type]]
if extname && File.extname(source) != extname
extname
else
nil
end
end
# Maps asset types to public directory.
ASSET_PUBLIC_DIRECTORIES = {
audio: "/audios",
font: "/fonts",
image: "/images",
javascript: "/javascripts",
stylesheet: "/stylesheets",
video: "/videos"
}
# Computes asset path to public directory. Plugins and
# extensions can override this method to point to custom assets
# or generate digested paths or query strings.
def compute_asset_path(source, options = {})
dir = ASSET_PUBLIC_DIRECTORIES[options[:type]] || ""
File.join(dir, source)
end
alias :public_compute_asset_path :compute_asset_path
# Pick an asset host for this source. Returns +nil+ if no host is set,
# the host if no wildcard is set, the host interpolated with the
# numbers 0-3 if it contains <tt>%d</tt> (the number is the source hash mod 4),
# or the value returned from invoking call on an object responding to call
# (proc or otherwise).
def compute_asset_host(source = "", options = {})
request = self.request if respond_to?(:request)
host = options[:host]
host ||= config.asset_host if defined? config.asset_host
if host
if host.respond_to?(:call)
arity = host.respond_to?(:arity) ? host.arity : host.method(:call).arity
args = [source]
args << request if request && (arity > 1 || arity < 0)
host = host.call(*args)
elsif host.include?("%d")
host = host % (Zlib.crc32(source) % 4)
end
end
host ||= request.base_url if request && options[:protocol] == :request
return unless host
if URI_REGEXP.match?(host)
host
else
protocol = options[:protocol] || config.default_asset_host_protocol || (request ? :request : :relative)
case protocol
when :relative
"//#{host}"
when :request
"#{request.protocol}#{host}"
else
"#{protocol}://#{host}"
end
end
end
# 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" # => /assets/xmlhr.js
# javascript_path "dir/xmlhr.js" # => /assets/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, options = {})
path_to_asset(source, { type: :javascript }.merge!(options))
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.
# Since +javascript_url+ is based on +asset_url+ method you can set +:host+ options. If +:host+
# options is set, it overwrites global +config.action_controller.asset_host+ setting.
#
# javascript_url "js/xmlhr.js", host: "http://stage.example.com" # => http://stage.example.com/assets/js/xmlhr.js
#
def javascript_url(source, options = {})
url_to_asset(source, { type: :javascript }.merge!(options))
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, .css 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" # => /assets/style.css
# stylesheet_path "dir/style.css" # => /assets/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, options = {})
path_to_asset(source, { type: :stylesheet }.merge!(options))
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.
# Since +stylesheet_url+ is based on +asset_url+ method you can set +:host+ options. If +:host+
# options is set, it overwrites global +config.action_controller.asset_host+ setting.
#
# stylesheet_url "css/style.css", host: "http://stage.example.com" # => http://stage.example.com/assets/css/style.css
#
def stylesheet_url(source, options = {})
url_to_asset(source, { type: :stylesheet }.merge!(options))
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, options = {})
path_to_asset(source, { type: :image }.merge!(options))
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.
# Since +image_url+ is based on +asset_url+ method you can set +:host+ options. If +:host+
# options is set, it overwrites global +config.action_controller.asset_host+ setting.
#
# image_url "edit.png", host: "http://stage.example.com" # => http://stage.example.com/assets/edit.png
#
def image_url(source, options = {})
url_to_asset(source, { type: :image }.merge!(options))
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, options = {})
path_to_asset(source, { type: :video }.merge!(options))
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.
# Since +video_url+ is based on +asset_url+ method you can set +:host+ options. If +:host+
# options is set, it overwrites global +config.action_controller.asset_host+ setting.
#
# video_url "hd.avi", host: "http://stage.example.com" # => http://stage.example.com/videos/hd.avi
#
def video_url(source, options = {})
url_to_asset(source, { type: :video }.merge!(options))
end
alias_method :url_to_video, :video_url # aliased to avoid conflicts with a 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, options = {})
path_to_asset(source, { type: :audio }.merge!(options))
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.
# Since +audio_url+ is based on +asset_url+ method you can set +:host+ options. If +:host+
# options is set, it overwrites global +config.action_controller.asset_host+ setting.
#
# audio_url "horse.wav", host: "http://stage.example.com" # => http://stage.example.com/audios/horse.wav
#
def audio_url(source, options = {})
url_to_asset(source, { type: :audio }.merge!(options))
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") # => /fonts/font
# font_path("font.ttf") # => /fonts/font.ttf
# font_path("dir/font.ttf") # => /fonts/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, options = {})
path_to_asset(source, { type: :font }.merge!(options))
end
alias_method :path_to_font, :font_path # aliased to avoid conflicts with a 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.
# Since +font_url+ is based on +asset_url+ method you can set +:host+ options. If +:host+
# options is set, it overwrites global +config.action_controller.asset_host+ setting.
#
# font_url "font.ttf", host: "http://stage.example.com" # => http://stage.example.com/fonts/font.ttf
#
def font_url(source, options = {})
url_to_asset(source, { type: :font }.merge!(options))
end
alias_method :url_to_font, :font_url # aliased to avoid conflicts with a font_url named route
end
end
end