aboutsummaryrefslogtreecommitdiffstats
path: root/actionpack/lib/action_view/renderer/partial_renderer.rb
blob: fc8a6b3107d06a8fe9795be48ec5953cda8b178b (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
require 'active_support/core_ext/object/blank'

module ActionView
  # = 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 "advertiser/_account.html.erb" with @buyer passed in as the local variable +account+, then
  # render "advertiser/_ad.html.erb" and pass the local variable +ad+ to the template for display.
  #
  # == The :as and :object options
  #
  # By default <tt>ActionView::Partials::PartialRenderer</tt> 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 +@buyer+ 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 "advertiser/_ad.html.erb" and pass the local variable +ad+ to the template for display. An
  # iteration counter will automatically be made available to the template with a name of the form
  # +partial_name_counter+. In the case of the example above, the template would be fed +ad_counter+.
  #
  # 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 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 "advertisement/_ad.html.erb" regardless of which controller this is being called from.
  #
  # == Rendering objects with the RecordIdentifier
  #
  # Instead of explicitly naming the location of a partial, you can also let the RecordIdentifier do the work if
  # you're following its conventions for RecordIdentifier#partial_path. Examples:
  #
  #  # @account is an Account instance, so it uses the RecordIdentifier to replace
  #  # <%= render :partial => "accounts/account", :locals => { :account => @account} %>
  #  <%= render :partial => @account %>
  #
  #  # @posts is an array of Post instances, so it uses the RecordIdentifier to 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 is an Account instance, so it uses the RecordIdentifier to replace
  #  # <%= render :partial => "accounts/account", :locals => { :account => @account } %>
  #  <%= render(@account) %>
  #
  #  # @posts is an array of Post instances, so it uses the RecordIdentifier to 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>
  #
  # 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 #:nodoc:
    def render(context, options, block)
      setup(context, options, block)

      wrap_formats(@path) do
        identifier = ((@template = find_partial) ? @template.identifier : @path)

        if @collection
          instrument(:collection, :identifier => identifier || "collection", :count => @collection.size) do
            render_collection
          end
        else
          instrument(:partial, :identifier => identifier) do
            render_partial
          end
        end
      end
    end

    def render_collection
      return nil if @collection.blank?

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

      result = @template ? collection_with_template : collection_without_template
      result.join(spacer).html_safe
    end

    def render_partial
      locals, view, block = @locals, @view, @block
      object, as = @object, @variable

      if !block && (layout = @options[:layout])
        layout = find_template(layout)
      end

      object ||= locals[as]
      locals[as] = object

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

      content = layout.render(view, locals){ content } if layout
      content
    end

    private

    def setup(context, options, block)
      @view   = context
      partial = options[:partial]

      @options = options
      @locals  = options[:locals] || {}
      @block   = block

      if String === partial
        @object     = options[:object]
        @path       = partial
        @collection = collection
      else
        @object = partial

        if @collection = collection_from_object || collection
          paths = @collection_data = @collection.map { |o| partial_path(o) }
          @path = paths.uniq.size == 1 ? paths.first : nil
        else
          @path = partial_path
        end
      end

      if @path
        @variable, @variable_counter = retrieve_variable(@path)
      else
        paths.map! { |path| retrieve_variable(path).unshift(path) }
      end
      if String === partial && @variable.to_s !~ /^[a-z_][a-zA-Z_0-9]*$/
        raise ArgumentError.new("The partial name (#{partial}) is not a valid Ruby identifier; " +
                                "make sure your partial name starts with a letter or underscore, " +
                                "and is followed by any combinations of letters, numbers, or underscores.")
      end

      self
    end

    def collection
      if @options.key?(:collection)
        collection = @options[:collection]
        collection.respond_to?(:to_ary) ? collection.to_ary : []
      end
    end

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

    def find_partial
      if path = @path
        locals = @locals.keys
        locals << @variable
        locals << @variable_counter if @collection
        find_template(path, locals)
      end
    end

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

    def collection_with_template
      segments, locals, template = [], @locals, @template
      as, counter = @variable, @variable_counter

      locals[counter] = -1

      @collection.each do |object|
        locals[counter] += 1
        locals[as] = object
        segments << template.render(@view, locals)
      end

      segments
    end

    def collection_without_template
      segments, locals, collection_data = [], @locals, @collection_data
      index, template, cache = -1, nil, {}
      keys = @locals.keys

      @collection.each_with_index do |object, i|
        path, *data = collection_data[i]
        template = (cache[path] ||= find_template(path, keys + data))
        locals[data[0]] = object
        locals[data[1]] = (index += 1)
        segments << template.render(@view, locals)
      end

      @template = template
      segments
    end

    PARTIAL_PATHS = {}

    def partial_path(object = @object)
      object = object.to_model if object.respond_to?(:to_model)

      path = if object.respond_to?(:to_path)
               object.to_path
             else
               ActiveSupport::Deprecation.warn "ActiveModel-compatible objects whose classes return a #model_name that responds to #partial_path are deprecated. Please respond to #to_path directly instead."
               object.class.model_name.partial_path
             end

      prefix = @lookup_context.prefixes.first
      PARTIAL_PATHS[ [path, prefix] ] ||= path.dup.tap do |object_path|
        merge_prefix_into_object_path(prefix, object_path)
      end
    end

    def merge_prefix_into_object_path(prefix, object_path)
      if prefix.include?(?/) && object_path.include?(?/)
        overlap = []
        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|
          overlap << dir if dir == object_path_array[index]
        end

        object_path.gsub!(/^#{overlap.join('/')}\//,'')
        object_path.insert(0, "#{File.dirname(prefix)}/")
      end
    end

    def retrieve_variable(path)
      variable = @options[:as].try(:to_sym) || path[%r'_?(\w+)(\.\w+)*$', 1].to_sym
      variable_counter = :"#{variable}_counter" if @collection
      [variable, variable_counter]
    end
  end
end