add some docs for ActionController::Renderers

1 files changed, 37 insertions, 0 deletions

diff --git a/actionpack/lib/action_controller/metal/renderers.rb b/actionpack/lib/action_controller/metal/renderers.rb
index d6f6ab1855..38711c8462 100644
--- a/actionpack/lib/action_controller/metal/renderers.rb
+++ b/actionpack/lib/action_controller/metal/renderers.rb
@@ -2,6 +2,7 @@ require 'active_support/core_ext/class/attribute'
 require 'active_support/core_ext/object/blank'
 
 module ActionController
+  # See <tt>Renderers.add</tt>
   def self.add_renderer(key, &block)
     Renderers.add(key, &block)
   end
@@ -39,7 +40,43 @@ module ActionController
       nil
     end
 
+    # Hash of available renderers, mapping a renderer name to its proc.
+    # Default keys are :json, :js, :xml and :update.
     RENDERERS = {}
+
+    # Adds a new renderer to call within controller actions.
+    # A renderer is invoked by passing its name as an option to
+    # <tt>AbstractController::Rendering#render</tt>. To create a renderer
+    # pass it a name and a block. The block takes two arguments, the first
+    # is the value paired with its key and the second is the remaining
+    # hash of options passed to +render+.
+    #
+    # === Example
+    # Create a csv renderer:
+    #
+    #   ActionController::Renderers.add :csv do |obj, options|
+    #     filename = options[:filename] || 'data'
+    #     str = obj.respond_to?(:to_csv) ? obj.to_csv : obj.to_s
+    #     send_data str, :type => Mime::CSV,
+    #       :disposition => "attachment; filename=#{filename}.csv"
+    #   end
+    #
+    # Note that we used Mime::CSV for the csv mime type as it comes with Rails.
+    # For a custom renderer, you'll need to register a mime type with
+    # <tt>Mime::Type.register</tt>.
+    #
+    # To use the csv renderer in a controller action:
+    #
+    #   def show
+    #     @csvable = Csvable.find(params[:id])
+    #     respond_to do |format|
+    #       format.html
+    #       format.csv { render :csv => @csvable, :filename => @csvable.name }
+    #     }
+    #   end
+    # To use renderers and their mime types in more concise ways, see
+    # <tt>ActionController::MimeResponds::ClassMethods.respond_to</tt> and
+    # <tt>ActionController::MimeResponds#respond_with</tt>
     def self.add(key, &block)
       define_method("_render_option_#{key}", &block)
       RENDERERS[key] = block