Enabling article dates in Nesta URLs

app.rb

# This code enables URLs with dates in for pages that have date set.
#
# If you use this code then a page published on 27 September 2010 with a path
# (relative to Nesta's content directory) of /foo/bar will now be available
# from /2010/09/07/foo/bar.
#
# Installation:
#
# $ mkdir -p local
# $ cat >> local/app.rb  # (paste the following code, then press ^D)

class Page
  def self.find_by_path_and_date(path, year, month, day)
    page = find_by_path(path)
    page.published_on?(year, month, day) ? page : nil
  end
  
  def published_on?(year, month, day)
    date = self.date
    date.year == year.to_i && date.month == month.to_i && date.day == day.to_i
  end

  def abspath
    date.nil? ? super : File.join("/" + date.strftime("%Y/%m/%d"), super)
  end
end

get "/:year/:month/:day/*" do
  set_common_variables
  parts = params[:splat].map { |p| p.sub(/\/$/, "") }
  @page = Page.find_by_path_and_date(
      File.join(parts), params[:year], params[:month], params[:day])
  raise Sinatra::NotFound if @page.nil?
  set_title(@page)
  set_from_page(:description, :keywords)
  cache haml(:page)
end