Rubyists

The code uses the FasterCSV gem so you'll need that installed. One gotcha i noticed is that if format.csv is before format.html in the respond_to block the request gets sent incorrectly.

Code

---

RAILS_ROOT/config/initializers/template_handlers.rb

require 'rcsv_template_handler'
ActionView::Template.register_template_handler :rcsv, ActionView::TemplateHandlers::RCSV

RAILS_ROOT/lib/rcsv_template_handler.rb

require 'fastercsv'

module ActionView
  module TemplateHandlers
    class RCSV < TemplateHandler
      include Compilable

      def self.line_offset
        2
      end

      def compile(template)
        content_type_handler = (@view.send!(:controller).respond_to?(:response) ? "controller.response" : "controller")
        "#{content_type_handler}.content_type ||= Mime::CSV
" +
        "if controller.request.env['HTTP_USER_AGENT'] =~ /msie/i
" +
        "  controller.headers['Pragma'] = 'public'
" +
        "  #{content_type_handler}.content_type ||= Mime::TEXT
" +
        "  controller.headers['Cache-Control'] = 'no-cache, must-revalidate, post-check=0, pre-check=0'
" +
        "  controller.headers['Expires'] = '0'
" +
        "else
" +
        "  #{content_type_handler.content_type ||= Mime::CSV
" +
        "end
" +
        "csv_doc = ::FasterCSV.new(:row_sep = "
") do |csv|
#{template.source}
end"
      end

      def cache_fragment(block, name = {}, options = nil)
        @view.fragment_for(block, name, options) do
          eval('csv_doc', block.binding)
        end
      end
    end
  end
end

Usage

---

RAILS_ROOT/app/controllers/name_controller.rb

class NameController < ApplicationController
  def action
    @data = Data.find :all
    respond_to do |format|
      format.html # Render action.html.erb
      format.csv  # Render action.csv.rcsv
    end
  end
end

RAILS_ROOT/app/view/name/action.csv.rcsv

@data.each do |datum|
  csv << datum
end