aboutsummaryrefslogtreecommitdiffstats
path: root/actionpack/lib/action_view/helpers/asset_url_helper.rb
blob: 71b78cf0b54edfc7488e5fb957c0e50cb90ff70b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
require 'zlib'

module ActionView
  # = Action View Asset URL Helpers
  module 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 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"
    #   )
    #
    module AssetUrlHelper
      URI_REGEXP = %r{^[-a-z]+://|^(?:cid|data):|^//}

      # Computes the path to asset in public directory. If :type
      # options is set, a file extension will be appended and scoped
      # to the corresponding public directory.
      #
      # All other asset *_path helpers delegate through this method.
      #
      #   asset_path "application.js"                     # => /application.js
      #   asset_path "application", type: :javascript     # => /javascripts/application.js
      #   asset_path "application", type: :stylesheet     # => /stylesheets/application.css
      #   asset_path "http://www.example.com/js/xmlhr.js" # => http://www.example.com/js/xmlhr.js
      def asset_path(source, options = {})
        source = source.to_s
        return "" unless source.present?
        return source if source =~ URI_REGEXP

        tail, source = source[/([\?#].+)$/], source.sub(/([\?#].+)$/, '')

        if extname = compute_asset_extname(source, options)
          source = "#{source}#{extname}"
        end

        if source[0] != ?/
          source = compute_asset_path(source, options)
        end

        relative_url_root = defined?(config.relative_url_root) && config.relative_url_root
        if relative_url_root
          source = "#{relative_url_root}#{source}" unless source.starts_with?("#{relative_url_root}/")
        end

        if host = compute_asset_host(source, options)
          source = "#{host}#{source}"
        end

        "#{source}#{tail}"
      end
      alias_method :path_to_asset, :asset_path # aliased to avoid conflicts with a asset_path named route

      # Computes the full URL to a asset in the public directory. This
      # will use +asset_path+ internally, so most of their behaviors
      # will be the same.
      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]]
        extname if extname && File.extname(source) != extname
      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

      # 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 = config.asset_host if defined? config.asset_host
        host ||= request.base_url if request && options[:protocol] == :request
        return unless 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 =~ /%d/
          host = host % (Zlib.crc32(source) % 4)
        end

        if host =~ URI_REGEXP
          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"                              # => /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, 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.
      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, <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, 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.
      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.
      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.
      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 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, 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.
      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")                                           # => /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, options = {})
        path_to_asset(source, {type: :font}.merge!(options))
      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, options = {})
        url_to_asset(source, {type: :font}.merge!(options))
      end
      alias_method :url_to_font, :font_url # aliased to avoid conflicts with an font_url named route
    end
  end
end