aboutsummaryrefslogtreecommitdiffstats
path: root/actionview/lib/action_view/renderer/partial_renderer.rb
blob: f175c30aa12759440da4a42e4a6cc3812e17c219 (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
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
# frozen_string_literal: true

require "concurrent/map"
require "action_view/renderer/partial_renderer/collection_caching"

module ActionView
  class PartialIteration
    # The number of iterations that will be done by the partial.
    attr_reader :size

    # The current iteration of the partial.
    attr_reader :index

    def initialize(size)
      @size  = size
      @index = 0
    end

    # Check if this is the first iteration of the partial.
    def first?
      index == 0
    end

    # Check if this is the last iteration of the partial.
    def last?
      index == size - 1
    end

    def iterate! # :nodoc:
      @index += 1
    end
  end

  # = Action View Partials
  #
  # There's also a convenience method for rendering sub templates within the current controller that depends on a
  # single object (we call this kind of sub templates for partials). It relies on the fact that partials should
  # follow the naming convention of being prefixed with an underscore -- as to separate them from regular
  # templates that could be rendered on their own.
  #
  # In a template for Advertiser#account:
  #
  #  <%= render partial: "account" %>
  #
  # This would render "advertiser/_account.html.erb".
  #
  # In another template for Advertiser#buy, we could have:
  #
  #   <%= render partial: "account", locals: { account: @buyer } %>
  #
  #   <% @advertisements.each do |ad| %>
  #     <%= render partial: "ad", locals: { ad: ad } %>
  #   <% end %>
  #
  # This would first render <tt>advertiser/_account.html.erb</tt> with <tt>@buyer</tt> passed in as the local variable +account+, then
  # render <tt>advertiser/_ad.html.erb</tt> and pass the local variable +ad+ to the template for display.
  #
  # == The :as and :object options
  #
  # By default ActionView::PartialRenderer doesn't have any local variables.
  # The <tt>:object</tt> option can be used to pass an object to the partial. For instance:
  #
  #   <%= render partial: "account", object: @buyer %>
  #
  # would provide the <tt>@buyer</tt> object to the partial, available under the local variable +account+ and is
  # equivalent to:
  #
  #   <%= render partial: "account", locals: { account: @buyer } %>
  #
  # With the <tt>:as</tt> option we can specify a different name for said local variable. For example, if we
  # wanted it to be +user+ instead of +account+ we'd do:
  #
  #   <%= render partial: "account", object: @buyer, as: 'user' %>
  #
  # This is equivalent to
  #
  #   <%= render partial: "account", locals: { user: @buyer } %>
  #
  # == \Rendering a collection of partials
  #
  # The example of partial use describes a familiar pattern where a template needs to iterate over an array and
  # render a sub template for each of the elements. This pattern has been implemented as a single method that
  # accepts an array and renders a partial by the same name as the elements contained within. So the three-lined
  # example in "Using partials" can be rewritten with a single line:
  #
  #   <%= render partial: "ad", collection: @advertisements %>
  #
  # This will render <tt>advertiser/_ad.html.erb</tt> and pass the local variable +ad+ to the template for display. An
  # iteration object will automatically be made available to the template with a name of the form
  # +partial_name_iteration+. The iteration object has knowledge about which index the current object has in
  # the collection and the total size of the collection. The iteration object also has two convenience methods,
  # +first?+ and +last?+. In the case of the example above, the template would be fed +ad_iteration+.
  # For backwards compatibility the +partial_name_counter+ is still present and is mapped to the iteration's
  # +index+ method.
  #
  # The <tt>:as</tt> option may be used when rendering partials.
  #
  # You can specify a partial to be rendered between elements via the <tt>:spacer_template</tt> option.
  # The following example will render <tt>advertiser/_ad_divider.html.erb</tt> between each ad partial:
  #
  #   <%= render partial: "ad", collection: @advertisements, spacer_template: "ad_divider" %>
  #
  # If the given <tt>:collection</tt> is +nil+ or empty, <tt>render</tt> will return +nil+. This will allow you
  # to specify a text which will be displayed instead by using this form:
  #
  #   <%= render(partial: "ad", collection: @advertisements) || "There's no ad to be displayed" %>
  #
  # NOTE: Due to backwards compatibility concerns, the collection can't be one of hashes. Normally you'd also
  # just keep domain objects, like Active Records, in there.
  #
  # == \Rendering shared partials
  #
  # Two controllers can share a set of partials and render them like this:
  #
  #   <%= render partial: "advertisement/ad", locals: { ad: @advertisement } %>
  #
  # This will render the partial <tt>advertisement/_ad.html.erb</tt> regardless of which controller this is being called from.
  #
  # == \Rendering objects that respond to +to_partial_path+
  #
  # Instead of explicitly naming the location of a partial, you can also let PartialRenderer do the work
  # and pick the proper path by checking +to_partial_path+ method.
  #
  #  # @account.to_partial_path returns 'accounts/account', so it can be used to replace:
  #  # <%= render partial: "accounts/account", locals: { account: @account} %>
  #  <%= render partial: @account %>
  #
  #  # @posts is an array of Post instances, so every post record returns 'posts/post' on +to_partial_path+,
  #  # that's why we can replace:
  #  # <%= render partial: "posts/post", collection: @posts %>
  #  <%= render partial: @posts %>
  #
  # == \Rendering the default case
  #
  # If you're not going to be using any of the options like collections or layouts, you can also use the short-hand
  # defaults of render to render partials. Examples:
  #
  #  # Instead of <%= render partial: "account" %>
  #  <%= render "account" %>
  #
  #  # Instead of <%= render partial: "account", locals: { account: @buyer } %>
  #  <%= render "account", account: @buyer %>
  #
  #  # @account.to_partial_path returns 'accounts/account', so it can be used to replace:
  #  # <%= render partial: "accounts/account", locals: { account: @account} %>
  #  <%= render @account %>
  #
  #  # @posts is an array of Post instances, so every post record returns 'posts/post' on +to_partial_path+,
  #  # that's why we can replace:
  #  # <%= render partial: "posts/post", collection: @posts %>
  #  <%= render @posts %>
  #
  # == \Rendering partials with layouts
  #
  # Partials can have their own layouts applied to them. These layouts are different than the ones that are
  # specified globally for the entire action, but they work in a similar fashion. Imagine a list with two types
  # of users:
  #
  #   <%# app/views/users/index.html.erb %>
  #   Here's the administrator:
  #   <%= render partial: "user", layout: "administrator", locals: { user: administrator } %>
  #
  #   Here's the editor:
  #   <%= render partial: "user", layout: "editor", locals: { user: editor } %>
  #
  #   <%# app/views/users/_user.html.erb %>
  #   Name: <%= user.name %>
  #
  #   <%# app/views/users/_administrator.html.erb %>
  #   <div id="administrator">
  #     Budget: $<%= user.budget %>
  #     <%= yield %>
  #   </div>
  #
  #   <%# app/views/users/_editor.html.erb %>
  #   <div id="editor">
  #     Deadline: <%= user.deadline %>
  #     <%= yield %>
  #   </div>
  #
  # ...this will return:
  #
  #   Here's the administrator:
  #   <div id="administrator">
  #     Budget: $<%= user.budget %>
  #     Name: <%= user.name %>
  #   </div>
  #
  #   Here's the editor:
  #   <div id="editor">
  #     Deadline: <%= user.deadline %>
  #     Name: <%= user.name %>
  #   </div>
  #
  # If a collection is given, the layout will be rendered once for each item in
  # the collection. For example, these two snippets have the same output:
  #
  #   <%# app/views/users/_user.html.erb %>
  #   Name: <%= user.name %>
  #
  #   <%# app/views/users/index.html.erb %>
  #   <%# This does not use layouts %>
  #   <ul>
  #     <% users.each do |user| -%>
  #       <li>
  #         <%= render partial: "user", locals: { user: user } %>
  #       </li>
  #     <% end -%>
  #   </ul>
  #
  #   <%# app/views/users/_li_layout.html.erb %>
  #   <li>
  #     <%= yield %>
  #   </li>
  #
  #   <%# app/views/users/index.html.erb %>
  #   <ul>
  #     <%= render partial: "user", layout: "li_layout", collection: users %>
  #   </ul>
  #
  # Given two users whose names are Alice and Bob, these snippets return:
  #
  #   <ul>
  #     <li>
  #       Name: Alice
  #     </li>
  #     <li>
  #       Name: Bob
  #     </li>
  #   </ul>
  #
  # The current object being rendered, as well as the object_counter, will be
  # available as local variables inside the layout template under the same names
  # as available in the partial.
  #
  # You can also apply a layout to a block within any template:
  #
  #   <%# app/views/users/_chief.html.erb %>
  #   <%= render(layout: "administrator", locals: { user: chief }) do %>
  #     Title: <%= chief.title %>
  #   <% end %>
  #
  # ...this will return:
  #
  #   <div id="administrator">
  #     Budget: $<%= user.budget %>
  #     Title: <%= chief.name %>
  #   </div>
  #
  # As you can see, the <tt>:locals</tt> hash is shared between both the partial and its layout.
  #
  # If you pass arguments to "yield" then this will be passed to the block. One way to use this is to pass
  # an array to layout and treat it as an enumerable.
  #
  #   <%# app/views/users/_user.html.erb %>
  #   <div class="user">
  #     Budget: $<%= user.budget %>
  #     <%= yield user %>
  #   </div>
  #
  #   <%# app/views/users/index.html.erb %>
  #   <%= render layout: @users do |user| %>
  #     Title: <%= user.title %>
  #   <% end %>
  #
  # This will render the layout for each user and yield to the block, passing the user, each time.
  #
  # You can also yield multiple times in one layout and use block arguments to differentiate the sections.
  #
  #   <%# app/views/users/_user.html.erb %>
  #   <div class="user">
  #     <%= yield user, :header %>
  #     Budget: $<%= user.budget %>
  #     <%= yield user, :footer %>
  #   </div>
  #
  #   <%# app/views/users/index.html.erb %>
  #   <%= render layout: @users do |user, section| %>
  #     <%- case section when :header -%>
  #       Title: <%= user.title %>
  #     <%- when :footer -%>
  #       Deadline: <%= user.deadline %>
  #     <%- end -%>
  #   <% end %>
  class PartialRenderer < AbstractRenderer
    include CollectionCaching

    PREFIXED_PARTIAL_NAMES = Concurrent::Map.new do |h, k|
      h[k] = Concurrent::Map.new
    end

    def initialize(*)
      super
      @context_prefix = @lookup_context.prefixes.first
    end

    def render(context, options, block)
      setup(context, options, block)
      @template = find_partial

      @lookup_context.rendered_format ||= begin
        if @template && @template.formats.present?
          @template.formats.first
        else
          formats.first
        end
      end

      if @collection
        render_collection
      else
        render_partial
      end
    end

    private

      def render_collection
        instrument(:collection, count: @collection.size) do |payload|
          return nil if @collection.blank?

          if @options.key?(:spacer_template)
            spacer = find_template(@options[:spacer_template], @locals.keys).render(@view, @locals)
          end

          cache_collection_render(payload) do
            @template ? collection_with_template : collection_without_template
          end.join(spacer).html_safe
        end
      end

      def render_partial
        instrument(:partial) do |payload|
          view, locals, block = @view, @locals, @block
          object, as = @object, @variable

          if !block && (layout = @options[:layout])
            layout = find_template(layout.to_s, @template_keys)
          end

          object = locals[as] if object.nil? # Respect object when object is false
          locals[as] = object if @has_object

          content = @template.render(view, locals) do |*name|
            view._layout_for(*name, &block)
          end

          content = layout.render(view, locals) { content } if layout
          payload[:cache_hit] = view.view_renderer.cache_hits[@template.virtual_path]
          content
        end
      end

      # Sets up instance variables needed for rendering a partial. This method
      # finds the options and details and extracts them. The method also contains
      # logic that handles the type of object passed in as the partial.
      #
      # If +options[:partial]+ is a string, then the <tt>@path</tt> instance variable is
      # set to that string. Otherwise, the +options[:partial]+ object must
      # respond to +to_partial_path+ in order to setup the path.
      def setup(context, options, block)
        @view = context
        @options = options
        @block   = block

        @locals  = options[:locals] || {}
        @details = extract_details(options)

        prepend_formats(options[:formats])

        partial = options[:partial]

        if String === partial
          @has_object = options.key?(:object)
          @object     = options[:object]
          @collection = collection_from_options
          @path       = partial
        else
          @has_object = true
          @object = partial
          @collection = collection_from_object || collection_from_options

          if @collection
            paths = @collection_data = @collection.map { |o| partial_path(o) }
            @path = paths.uniq.one? ? paths.first : nil
          else
            @path = partial_path
          end
        end

        if as = options[:as]
          raise_invalid_option_as(as) unless /\A[a-z_]\w*\z/.match?(as.to_s)
          as = as.to_sym
        end

        if @path
          @variable, @variable_counter, @variable_iteration = retrieve_variable(@path, as)
          @template_keys = retrieve_template_keys
        else
          paths.map! { |path| retrieve_variable(path, as).unshift(path) }
        end

        self
      end

      def collection_from_options
        if @options.key?(:collection)
          collection = @options[:collection]
          collection ? collection.to_a : []
        end
      end

      def collection_from_object
        @object.to_ary if @object.respond_to?(:to_ary)
      end

      def find_partial
        find_template(@path, @template_keys) if @path
      end

      def find_template(path, locals)
        prefixes = path.include?(?/) ? [] : @lookup_context.prefixes
        @lookup_context.find_template(path, prefixes, true, locals, @details)
      end

      def collection_with_template
        view, locals, template = @view, @locals, @template
        as, counter, iteration = @variable, @variable_counter, @variable_iteration

        if layout = @options[:layout]
          layout = find_template(layout, @template_keys)
        end

        partial_iteration = PartialIteration.new(@collection.size)
        locals[iteration] = partial_iteration

        @collection.map do |object|
          locals[as]        = object
          locals[counter]   = partial_iteration.index

          content = template.render(view, locals)
          content = layout.render(view, locals) { content } if layout
          partial_iteration.iterate!
          content
        end
      end

      def collection_without_template
        view, locals, collection_data = @view, @locals, @collection_data
        cache = {}
        keys  = @locals.keys

        partial_iteration = PartialIteration.new(@collection.size)

        @collection.map do |object|
          index = partial_iteration.index
          path, as, counter, iteration = collection_data[index]

          locals[as]        = object
          locals[counter]   = index
          locals[iteration] = partial_iteration

          template = (cache[path] ||= find_template(path, keys + [as, counter, iteration]))
          content = template.render(view, locals)
          partial_iteration.iterate!
          content
        end
      end

      # Obtains the path to where the object's partial is located. If the object
      # responds to +to_partial_path+, then +to_partial_path+ will be called and
      # will provide the path. If the object does not respond to +to_partial_path+,
      # then an +ArgumentError+ is raised.
      #
      # If +prefix_partial_path_with_controller_namespace+ is true, then this
      # method will prefix the partial paths with a namespace.
      def partial_path(object = @object)
        object = object.to_model if object.respond_to?(:to_model)

        path = if object.respond_to?(:to_partial_path)
          object.to_partial_path
        else
          raise ArgumentError.new("'#{object.inspect}' is not an ActiveModel-compatible object. It must implement :to_partial_path.")
        end

        if @view.prefix_partial_path_with_controller_namespace
          prefixed_partial_names[path] ||= merge_prefix_into_object_path(@context_prefix, path.dup)
        else
          path
        end
      end

      def prefixed_partial_names
        @prefixed_partial_names ||= PREFIXED_PARTIAL_NAMES[@context_prefix]
      end

      def merge_prefix_into_object_path(prefix, object_path)
        if prefix.include?(?/) && object_path.include?(?/)
          prefixes = []
          prefix_array = File.dirname(prefix).split("/")
          object_path_array = object_path.split("/")[0..-3] # skip model dir & partial

          prefix_array.each_with_index do |dir, index|
            break if dir == object_path_array[index]
            prefixes << dir
          end

          (prefixes << object_path).join("/")
        else
          object_path
        end
      end

      def retrieve_template_keys
        keys = @locals.keys
        keys << @variable if @has_object || @collection
        if @collection
          keys << @variable_counter
          keys << @variable_iteration
        end
        keys
      end

      def retrieve_variable(path, as)
        variable = as || begin
          base = path[-1] == "/" ? "" : File.basename(path)
          raise_invalid_identifier(path) unless base =~ /\A_?(.*?)(?:\.\w+)*\z/
          $1.to_sym
        end
        if @collection
          variable_counter = :"#{variable}_counter"
          variable_iteration = :"#{variable}_iteration"
        end
        [variable, variable_counter, variable_iteration]
      end

      IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " \
                                 "make sure your partial name starts with underscore."

      OPTION_AS_ERROR_MESSAGE  = "The value (%s) of the option `as` is not a valid Ruby identifier; " \
                                 "make sure it starts with lowercase letter, " \
                                 "and is followed by any combination of letters, numbers and underscores."

      def raise_invalid_identifier(path)
        raise ArgumentError.new(IDENTIFIER_ERROR_MESSAGE % (path))
      end

      def raise_invalid_option_as(as)
        raise ArgumentError.new(OPTION_AS_ERROR_MESSAGE % (as))
      end
  end
end