// get started with ubuntu 7.1
// e.g. on a new slice from http://slicehost.com !

# 1) make yrself a user and stop being root

# 2) main web stack + ruby
sudo aptitude install -y make screen
sudo aptitude install -y apache2 php5 mysql-server
sudo aptitude install -y subversion postfix
sudo aptitude install -y ruby1.8 ruby1.8-dev rubygems irb
sudo aptitude install -y imagemagick librmagick-ruby1.8 librmagick-ruby-doc libfreetype6-dev xml-core

# 3) gemz
# rubygems appears to be broken as hell. 
# gem update --system does squat
# had to manually d/l rubygems 1.0.1, ruby setup.rb
wget http://rubyforge.org/frs/download.php/29548/rubygems-1.0.1.tgz
tar xzvf rubygems-1.0.1.tgz
cd rubygems-1.0.1
sudo ruby setup.rb
sudo gem install rails mongrel merb map_by_method

// Just throw this at the bottom of your application.js and you’re good to go: all jQuery ajax requests will trigger the wants.js block of your respond_to declaration, exactly like you’d expect. Enjoy.
// via: http://ozmm.org/posts/jquery_and_respond_to.html

jQuery.ajaxSetup({ ‘beforeSend’: function(xhr) {xhr.setRequestHeader(“Accept”, “text/javascript”)} })

// ActiveRecord plugin for managing state changes
// elitists.textdriven.com/svn/plugins/acts_as_state_machine/

class Something < ActiveRecord::Base

  # Validations
  validate :validate_state_change

  # State Machine States
  acts_as_state_machine :initial => :new
  state :new
  state :enabled,   :after => :after_enabled
  state :disabled,  :after => :after_disabled

  # State Machine Events
  event :enabled do
    transitions :from => :new,      :to => :enabled
    transitions :from => :disabled, :to => :enabled
  end
  
  event :disabled do
    transitions :from => :new,      :to => :disabled
    transitions :from => :enabled,  :to => :disabled
  end

  # Instance Methods
  def validate_state_change
    return if new_record?
    old = self.class.find(id)
    old_state = old.state
    new_state = self.state
    self.state = old_state
    if old_state != new_state
      begin
        if self.method("#{new_state}!").call != true
          errors.add(:state, "cannot transition from #{old_state} to #{new_state}")
        end
      rescue NameError
      end
      self.state = new_state
    end
  end
end

# load production data, still needs some polish
# based on code from http://push.cx/2007/capistrano-task-to-load-production-data
# cap 2.0 compatible
# exec is being weird, had to end w/ a syscall :\ any ideas?

desc "Load production data into development database"
task :load_production_data, :roles => :db, :only => { :primary => true } do
  require 'yaml'
  ['config/database.yml'].each do |file|

    database = YAML::load_file(file)

    filename = "dump.#{Time.now.strftime '%Y-%m-%d_%H:%M:%S'}.sql.gz"
    # on_rollback { delete "/tmp/#{filename}" }

    # run "mysqldump -u #{database['production']['username']} --password=#{database['production']['password']} #{database['production']['database']} > /tmp/#{filename}" do |channel, stream, data|
    run "mysqldump -h #{database['production']['host']} -u #{database['production']['username']} --password=#{database['production']['password']} #{database['production']['database']} | gzip > /tmp/#{filename}" do |channel, stream, data|
      puts data
    end
    get "/tmp/#{filename}", filename
    # exec "/tmp/#{filename}"
    password = database['development']['password'].nil? ? '' : "--password=#{database['development']['password']}"  # FIXME pass shows up in process list, do not use in shared hosting!!! Use a .my.cnf instead
    # FIXME exec and run w/ localhost as host not working :\
    # exec "mysql -u #{database['development']['username']} #{password} #{database['development']['database']} < #{filename}; rm -f #{filename}"
    `gunzip -c #{filename} | mysql -u #{database['development']['username']} #{password} #{database['development']['database']} && rm -f gunzip #{filename}`
  end
  
end

Essential for degradable javascript, when one never knows if a view or partial is being called via XmlHttpRequest or not. Throw the below code in your ApplicationController (application.rb)

More info in this blog post

def render(*args)
        args.first[:layout] = false if request.xhr? and args.first[:layout].nil?
        super
end

A oneline helper I put in all of my apps. Looks for HTTP headers that signal you're being called via an XmlHttpRequest. I use it for instant degradable AJAX by rendering a template if it's as usual but just rendering a partial if they just want that part!

  def ajax_request?
    request.env['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest' || params[:ajax]  # params[:ajax] for safe-keeping, FIXME if it works w/ all browsers
  end