application_controller.rb

# Forked from user dirk; changed to drop the should_render boolean arg and
# replace it with a separate method, cache_and_render

class ApplicationController < ActionController::Base
  # Other random stuff.
  
  protected

  def cache_and_render(key, opts = {})
    cached = cache(key, opts)
    render :text => cached
    return cached
  end
  
  def cache(key, opts = {})
    cache = read_fragment(key, opts)
    if not cache
      cache = yield
      write_fragment(key, cache, opts)
    end
    return cache
  end
end

class Controller < ApplicationController
  def action
    # Filtering or other random stuff.
    cache('key', :expires_in => 5.minutes) do
      "This will be cached and rendered."
    end
    # This will be cached as well, but stored in cached_data instead of being rendered.
    cached_data = cache('other_key', {}, false) { User.first.email }
  end
end