Begin unifying the interface between ActionController and ActionView

1 files changed, 300 insertions, 0 deletions

diff --git a/actionpack/lib/action_view/render/partials.rb b/actionpack/lib/action_view/render/partials.rb
new file mode 100644
index 0000000000..aa4c4af213
--- /dev/null
+++ b/actionpack/lib/action_view/render/partials.rb
@@ -0,0 +1,300 @@
+module ActionView
+  # 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.erb" and pass the instance variable @account in as a local variable
+  # +account+ to the template for display.
+  #
+  # In another template for Advertiser#buy, we could have:
+  #
+  #   <%= render :partial => "account", :locals => { :account => @buyer } %>
+  #
+  #   <% for ad in @advertisements %>
+  #     <%= render :partial => "ad", :locals => { :ad => ad } %>
+  #   <% end %>
+  #
+  # This would first render "advertiser/_account.erb" with @buyer passed in as the local variable +account+, then
+  # render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display.
+  #
+  # == 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.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+.
+  #
+  # 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.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 => @buyer } %>
+  #  <%= 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: $<%= user.budget %>
+  #     <%= yield user, :footer %>
+  #   </div>
+  #
+  #   <%# app/views/users/index.html.erb &>
+  #   <% render :layout => @users do |user, section| %>
+  #     <%- case section when :header -%>
+  #       Title: <%= user.title %>
+  #     <%- when :footer -%>
+  #       Deadline: <%= user.deadline %>
+  #     <%- end -%>
+  #   <% end %>
+  module Partials
+    extend ActiveSupport::Memoizable
+
+    def _render_partial(options = {}) #:nodoc:
+      options[:locals] ||= {}
+
+      case path = partial = options[:partial]        
+      when *_array_like_objects
+        return _render_partial_collection(partial, options)
+      else
+        if partial.is_a?(ActionView::Helpers::FormBuilder)
+          path = partial.class.to_s.demodulize.underscore.sub(/_builder$/, '')
+          options[:locals].merge!(path.to_sym => partial)
+        elsif !partial.is_a?(String)
+          options[:object] = object = partial
+          path = ActionController::RecordIdentifier.partial_path(object, controller_path)
+        end
+        _, _, prefix, object = parts = partial_parts(path, options)
+        template = find_by_parts(*parts)
+        _render_partial_object(template, options, (object unless object == true))
+      end
+    end
+
+    private
+      def partial_parts(name, options)
+        segments = name.split("/")
+        parts = segments.pop.split(".")
+
+        case parts.size
+        when 1
+          parts
+        when 2, 3
+          extension = parts.delete_at(1).to_sym
+          if formats.include?(extension)
+            self.formats.replace [extension]
+          end
+          parts.pop if parts.size == 2
+        end
+
+        path = parts.join(".")
+        prefix = segments[0..-1].join("/")
+        prefix = prefix.blank? ? controller_path : prefix
+        parts = [path, formats, prefix]
+        parts.push options[:object] || true
+      end
+
+      def _render_partial_with_block(layout, block, options)
+        @_proc_for_layout = block
+        concat(_render_partial(options.merge(:partial => layout)))
+      ensure
+        @_proc_for_layout = nil
+      end
+  
+      def _render_partial_with_layout(layout, options)
+        if layout
+          prefix = controller && !layout.include?("/") ? controller.controller_path : nil
+          layout = find_by_parts(layout, formats, prefix, true)
+        end
+        content = _render_partial(options)
+        return _render_content_with_layout(content, layout, options[:locals])
+      end
+    
+      def _deprecated_ivar_assign(template)
+        if respond_to?(:controller)
+          ivar = :"@#{template.variable_name}"
+          object =
+            if controller.instance_variable_defined?(ivar)
+              ActiveSupport::Deprecation::DeprecatedObjectProxy.new(
+                controller.instance_variable_get(ivar),
+                "#{ivar} will no longer be implicitly assigned to #{template.variable_name}")
+            end
+        end
+      end
+
+      def _array_like_objects
+        array_like = [Array]
+        if defined?(ActiveRecord)
+          array_like.push(ActiveRecord::Associations::AssociationCollection, ActiveRecord::NamedScope::Scope)
+        end
+        array_like
+      end
+
+      def _render_partial_object(template, options, object = nil)
+        if options.key?(:collection)
+          _render_partial_collection(options.delete(:collection), options, template)
+        else
+          locals = (options[:locals] ||= {})
+          object ||= locals[:object] || locals[template.variable_name]
+          
+          _set_locals(object, locals, template, options)          
+          _render_template(template, locals)
+        end
+      end
+
+      def _set_locals(object, locals, template, options)
+        object ||= _deprecated_ivar_assign(template)
+        locals[:object] = locals[template.variable_name] = object
+        locals[options[:as]] = object if options[:as]
+      end
+
+      def _render_partial_collection(collection, options = {}, passed_template = nil) #:nodoc:
+        return nil if collection.blank?
+        
+        spacer = options[:spacer_template] ? _render_partial(:partial => options[:spacer_template]) : ''
+
+        locals = (options[:locals] ||= {})
+        index, @_partial_path = 0, nil
+        collection.map do |object|
+          template = passed_template || begin
+            _partial_path = 
+              ActionController::RecordIdentifier.partial_path(object, controller_path)
+            template = _pick_partial_template(_partial_path)
+          end
+
+          _set_locals(object, locals, template, options)
+          locals[template.counter_name] = index
+          
+          index += 1
+          _render_template(template, locals)
+        end.join(spacer)
+      end
+
+      def _pick_partial_template(partial_path) #:nodoc:
+        prefix = controller_path unless partial_path.include?('/')
+        find_by_parts(partial_path, formats, prefix, true)
+      end
+      memoize :_pick_partial_template
+  end
+end