Application Controller.rb

# Filters added to this controller apply to all controllers in the application.
# Likewise, all the methods added will be available for all controllers.

class ApplicationController < ActionController::Base
  include Clearance::Authentication
  helper :all # include all helpers, all the time
  protect_from_forgery # See ActionController::RequestForgeryProtection for details
  
  # Scrub sensitive parameters from your log
  # filter_parameter_logging :password

  def render_optional_error_file(status_code)
    super unless render_error(status_code)
  end

  def render_error(error_type)
    case error_type
      when :not_found
        @message = 'Page Not Found.'
        @error_code = 404
      when :internal_server_error
        @message = 'Something has gone wrong.'
        @error_code = 500
      else
        return false
    end
    
    respond_to do |type| 
      type.html { render :template => "errors/error", :layout => 'application', :status => error_type }
      type.all  { render :nothing => true, :status => error_type } 
    end
    true
  end

end

Application layout.haml

!!!
%html
  %head
    %title= "Postal Proxy"
    = stylesheet_link_tag 'application'
    = javascript_include_tag :all
    
  %body(id=controller_name class=action_name)
    = render :partial => 'layouts/flash_messages' if flash.present?
    = render :partial => 'layouts/header'
    
    #content
      .frame= yield
    
    = render :partial => 'layouts/footer'
    
    %script(language="javascript" type="text/javascript" src="http://quickribbon.com/ribbon/2009/08/a798930f47f6eee0967cd49380dea890.js")

Form partial.haml

%h1.page_title Send a Postcard
 
-form_for @postcard do |f|
  %fieldset.message_box
    =f.label :body, '3. Your Message'
    =f.text_area :body, :tabindex => '3'
 
  %fieldset.address_box
    =f.label :to_address, '1. To Address'
    =f.text_area :to_address, :tabindex => '1'
 
  %fieldset.address_box
    =f.label :from_address, '2. From Address'
    =f.text_area :from_address, :tabindex => '2'
 
  =link_to_function 'Save', "$(this).up('form').submit()", :class => 'button'
  =link_to 'Back', postcards_path, :class => 'button'
  =link_to('Delete', [@postcard], :method => 'delete', :confirm => 'Are you sure?', :class => 'button') unless @postcard.new_record?
.clear
 
:javascript
  Event.observe(window, 'load', function() {
    $("postcard_to_address").focus();
  });

gistfile5.txt

Sample Controller.rb

class PostcardsController < ApplicationController
  before_filter :authenticate
  before_filter :find_postcard, :only => [:show, :edit, :update, :destroy, :deliver]
  before_filter :ensure_unsent, :only => [:show, :edit, :deliver, :update]
  
  def index
    @unsent_postcards = current_user.postcards.unsent
    @sent_postcards   = current_user.postcards.sent
  end

  def show
    render :action => :edit
  end

  def new
    @postcard = current_user.postcards.new
  end

  def edit
  end

  def create
    if @postcard = current_user.postcards.create(params[:postcard])
      flash[:notice] = "Your postcard has been saved"
      redirect_to postcards_path
    else
      flash[:error] = "There was an error saving your postcard"
      render :action => 'new'
    end
  end

  def update
    if @postcard.update_attributes(params[:postcard])
      flash[:notice] = "Your postcard has been saved"
      redirect_to postcards_path
    else
      flash[:error] = "There was an error saving your postcard"
      render :action => 'edit'
    end
  end
  
  def deliver
    if @postcard.deliver!
      flash[:notice] = "Your postcard has been delivered"
    else
      flash[:error] = "There was an error delivering your postcard"
    end
    redirect_to postcards_path
  end

  def destroy
    if @postcard.destroy
      flash[:notice] = "Your postcard was successfully deleted"
      redirect_to postcards_path
    else
      flash[:error] = "Your postcard was not successfully deleted"
      redirect :back
    end
  end

protected
  
  def find_postcard
    @postcard = current_user.postcards.find(params[:id])
  end
  
  def ensure_unsent
    if @postcard.sent_at.present?
      flash[:error] = "This message has already been sent."
      redirect_to postcards_path and return
    end
  end
end