vendor/rails/actionpack/lib/action_view/partials.rb

   1 module ActionView
   2   # There's also a convenience method for rendering sub templates within the current controller that depends on a
   3   # single object (we call this kind of sub templates for partials). It relies on the fact that partials should
   4   # follow the naming convention of being prefixed with an underscore -- as to separate them from regular
   5   # templates that could be rendered on their own.
   6   #
   7   # In a template for Advertiser#account:
   8   #
   9   #  <%= render :partial => "account" %>
  10   #
  11   # This would render "advertiser/_account.erb" and pass the instance variable @account in as a local variable
  12   # +account+ to the template for display.
  13   #
  14   # In another template for Advertiser#buy, we could have:
  15   #
  16   #   <%= render :partial => "account", :locals => { :account => @buyer } %>
  17   #
  18   #   <% for ad in @advertisements %>
  19   #     <%= render :partial => "ad", :locals => { :ad => ad } %>
  20   #   <% end %>
  21   #
  22   # This would first render "advertiser/_account.erb" with @buyer passed in as the local variable +account+, then
  23   # render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display.
  24   #
  25   # == Rendering a collection of partials
  26   #
  27   # The example of partial use describes a familiar pattern where a template needs to iterate over an array and
  28   # render a sub template for each of the elements. This pattern has been implemented as a single method that
  29   # accepts an array and renders a partial by the same name as the elements contained within. So the three-lined
  30   # example in "Using partials" can be rewritten with a single line:
  31   #
  32   #   <%= render :partial => "ad", :collection => @advertisements %>
  33   #
  34   # This will render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display. An
  35   # iteration counter will automatically be made available to the template with a name of the form
  36   # +partial_name_counter+. In the case of the example above, the template would be fed +ad_counter+.
  37   #
  38   # NOTE: Due to backwards compatibility concerns, the collection can't be one of hashes. Normally you'd also
  39   # just keep domain objects, like Active Records, in there.
  40   #
  41   # == Rendering shared partials
  42   #
  43   # Two controllers can share a set of partials and render them like this:
  44   #
  45   #   <%= render :partial => "advertisement/ad", :locals => { :ad => @advertisement } %>
  46   #
  47   # This will render the partial "advertisement/_ad.erb" regardless of which controller this is being called from.
  48   #
  49   # == Rendering objects with the RecordIdentifier
  50   #
  51   # Instead of explicitly naming the location of a partial, you can also let the RecordIdentifier do the work if
  52   # you're following its conventions for RecordIdentifier#partial_path. Examples:
  53   #
  54   #  # @account is an Account instance, so it uses the RecordIdentifier to replace
  55   #  # <%= render :partial => "accounts/account", :locals => { :account => @buyer } %>
  56   #  <%= render :partial => @account %>
  57   #
  58   #  # @posts is an array of Post instances, so it uses the RecordIdentifier to replace
  59   #  # <%= render :partial => "posts/post", :collection => @posts %>
  60   #  <%= render :partial => @posts %>
  61   #
  62   # == Rendering the default case
  63   #
  64   # If you're not going to be using any of the options like collections or layouts, you can also use the short-hand
  65   # defaults of render to render partials. Examples:
  66   #
  67   #  # Instead of <%= render :partial => "account" %>
  68   #  <%= render "account" %>
  69   #
  70   #  # Instead of <%= render :partial => "account", :locals => { :account => @buyer } %>
  71   #  <%= render "account", :account => @buyer %>
  72   #
  73   #  # @account is an Account instance, so it uses the RecordIdentifier to replace
  74   #  # <%= render :partial => "accounts/account", :locals => { :account => @account } %>
  75   #  <%= render(@account) %>
  76   #
  77   #  # @posts is an array of Post instances, so it uses the RecordIdentifier to replace
  78   #  # <%= render :partial => "posts/post", :collection => @posts %>
  79   #  <%= render(@posts) %>
  80   #
  81   # == Rendering partials with layouts
  82   #
  83   # Partials can have their own layouts applied to them. These layouts are different than the ones that are
  84   # specified globally for the entire action, but they work in a similar fashion. Imagine a list with two types
  85   # of users:
  86   #
  87   #   <%# app/views/users/index.html.erb &>
  88   #   Here's the administrator:
  89   #   <%= render :partial => "user", :layout => "administrator", :locals => { :user => administrator } %>
  90   #
  91   #   Here's the editor:
  92   #   <%= render :partial => "user", :layout => "editor", :locals => { :user => editor } %>
  93   #
  94   #   <%# app/views/users/_user.html.erb &>
  95   #   Name: <%= user.name %>
  96   #
  97   #   <%# app/views/users/_administrator.html.erb &>
  98   #   <div id="administrator">
  99   #     Budget: $<%= user.budget %>
 100   #     <%= yield %>
 101   #   </div>
 102   #
 103   #   <%# app/views/users/_editor.html.erb &>
 104   #   <div id="editor">
 105   #     Deadline: <%= user.deadline %>
 106   #     <%= yield %>
 107   #   </div>
 108   #
 109   # ...this will return:
 110   #
 111   #   Here's the administrator:
 112   #   <div id="administrator">
 113   #     Budget: $<%= user.budget %>
 114   #     Name: <%= user.name %>
 115   #   </div>
 116   #
 117   #   Here's the editor:
 118   #   <div id="editor">
 119   #     Deadline: <%= user.deadline %>
 120   #     Name: <%= user.name %>
 121   #   </div>
 122   #
 123   # You can also apply a layout to a block within any template:
 124   #
 125   #   <%# app/views/users/_chief.html.erb &>
 126   #   <% render(:layout => "administrator", :locals => { :user => chief }) do %>
 127   #     Title: <%= chief.title %>
 128   #   <% end %>
 129   #
 130   # ...this will return:
 131   #
 132   #   <div id="administrator">
 133   #     Budget: $<%= user.budget %>
 134   #     Title: <%= chief.name %>
 135   #   </div>
 136   #
 137   # As you can see, the <tt>:locals</tt> hash is shared between both the partial and its layout.
 138   #
 139   # If you pass arguments to "yield" then this will be passed to the block. One way to use this is to pass
 140   # an array to layout and treat it as an enumerable.
 141   #
 142   #   <%# app/views/users/_user.html.erb &>
 143   #   <div class="user">
 144   #     Budget: $<%= user.budget %>
 145   #     <%= yield user %>
 146   #   </div>
 147   #
 148   #   <%# app/views/users/index.html.erb &>
 149   #   <% render :layout => @users do |user| %>
 150   #     Title: <%= user.title %>
 151   #   <% end %>
 152   #
 153   # This will render the layout for each user and yield to the block, passing the user, each time.
 154   #
 155   # You can also yield multiple times in one layout and use block arguments to differentiate the sections.
 156   #
 157   #   <%# app/views/users/_user.html.erb &>
 158   #   <div class="user">
 159   #     <%= yield user, :header %>
 160   #     Budget: $<%= user.budget %>
 161   #     <%= yield user, :footer %>
 162   #   </div>
 163   #
 164   #   <%# app/views/users/index.html.erb &>
 165   #   <% render :layout => @users do |user, section| %>
 166   #     <%- case section when :header -%>
 167   #       Title: <%= user.title %>
 168   #     <%- when :footer -%>
 169   #       Deadline: <%= user.deadline %>
 170   #     <%- end -%>
 171   #   <% end %>
 172   module Partials
 173     extend ActiveSupport::Memoizable
 174
 175     private
 176       def render_partial(options = {}) #:nodoc:
 177         local_assigns = options[:locals] || {}
 178
 179         case partial_path = options[:partial]
 180         when String, Symbol, NilClass
 181           if options.has_key?(:collection)
 182             render_partial_collection(options)
 183           else
 184             _pick_partial_template(partial_path).render_partial(self, options[:object], local_assigns)
 185           end
 186         when ActionView::Helpers::FormBuilder
 187           builder_partial_path = partial_path.class.to_s.demodulize.underscore.sub(/_builder$/, '')
 188           local_assigns.merge!(builder_partial_path.to_sym => partial_path)
 189           render_partial(:partial => builder_partial_path, :object => options[:object], :locals => local_assigns)
 190         else
 191           if Array === partial_path ||
 192             (defined?(ActiveRecord) &&
 193              (ActiveRecord::Associations::AssociationCollection === partial_path ||
 194               ActiveRecord::NamedScope::Scope === partial_path))
 195             render_partial_collection(options.except(:partial).merge(:collection => partial_path))
 196           else
 197             object = partial_path
 198             render_partial(
 199               :partial => ActionController::RecordIdentifier.partial_path(object, controller.class.controller_path),
 200               :object => object,
 201               :locals => local_assigns
 202             )
 203           end
 204         end
 205       end
 206
 207       def render_partial_collection(options = {}) #:nodoc:
 208         return nil if options[:collection].blank?
 209
 210         partial = options[:partial]
 211         spacer = options[:spacer_template] ? render(:partial => options[:spacer_template]) : ''
 212         local_assigns = options[:locals] ? options[:locals].clone : {}
 213         as = options[:as]
 214
 215         index = 0
 216         options[:collection].map do |object|
 217           _partial_path ||= partial ||
 218             ActionController::RecordIdentifier.partial_path(object, controller.class.controller_path)
 219           template = _pick_partial_template(_partial_path)
 220           local_assigns[template.counter_name] = index
 221           result = template.render_partial(self, object, local_assigns.dup, as)
 222           index += 1
 223           result
 224         end.join(spacer)
 225       end
 226
 227       def _pick_partial_template(partial_path) #:nodoc:
 228         if partial_path.include?('/')
 229           path = File.join(File.dirname(partial_path), "_#{File.basename(partial_path)}")
 230         elsif controller
 231           path = "#{controller.class.controller_path}/_#{partial_path}"
 232         else
 233           path = "_#{partial_path}"
 234         end
 235
 236         self.view_paths.find_template(path, self.template_format)
 237       end
 238       memoize :_pick_partial_template
 239   end
 240 end