1  def minutes_in_words(timestamp)
   2      minutes = (((Time.now - timestamp).abs)/60).round
   3      
   4      return nil if minutes < 0
   5      
   6      case minutes
   7        when 0..4            then '&lt; 5 minutes'
   8        when 5..14           then '&lt; 15 minutes'
   9        when 15..29          then '&lt; 30 minutes'
  10        when 30..59          then '&gt; 30 minutes'
  11        when 60..119         then '&gt; 1 hour'
  12        when 120..239        then '&gt; 2 hours'
  13        when 240..479        then '&gt; 4 hours'
  14        when 480..719        then '&gt; 8 hours'
  15        when 720..1439       then '&gt; 12 hours'
  16        when 1440..11519     then '&gt; ' << pluralize((minutes/1440).floor, 'day')
  17        when 11520..43199    then '&gt; ' << pluralize((minutes/11520).floor, 'week')
  18        when 43200..525599   then '&gt; ' << pluralize((minutes/43200).floor, 'month')  
  19        else                      '&gt; ' << pluralize((minutes/525600).floor, 'år')
  20      end
  21    end

1. http://www.actsasflinn.com/articles/2007/04/10/time-ago-method-for-ruby-on-rails
2. http://timeago.yarp.com/

The model:

   1  class Category
   2  ...
   3    def recurse
   4      yield(self)
   5  
   6      children.each do |child|
   7        child.recurse {|sibling| yield sibling}
   8      end
   9    end
  10  end

The recusion:

   1  Category.root.recurse do |child|
   2    puts child
   3  end

This is an example of how to use ActiveRecord without Rails:

   1  ['/model', '/db'].each do |folder|
   2    $:.unshift File.dirname(__FILE__) + folder
   3  end
   4  
   5  require 'test/unit'
   6  require 'rubygems'
   7  require 'activerecord'
   8  
   9  ActiveRecord::Base.logger = Logger.new(File.dirname(__FILE__) + '/debug.log')
  10  ActiveRecord::Base.configurations = YAML::load(IO.read(File.dirname(__FILE__) + '/config/database.yml'))
  11  ActiveRecord::Base.establish_connection('sqlite3')
  12  
  13  require 'schema'
  14  

Schema contains, for example:

   1  ActiveRecord::Schema.define :version => 0 do
   2    create_table :languages, :force => true do |t|
   3      t.string :name
   4    end
   5  end

This snippets shows you how to create a daemon process out of an ordinary Ruby script.

First you’ll need the daemons gem:

   1  gem install daemons

Then you’ll need the daemon script, for example daemon.rb:

   1  require 'rubygems'
   2  require 'daemons'
   3  
   4  pwd  = File.dirname(File.expand_path(__FILE__))
   5  file = pwd + '/../lib/background_service.rb'
   6  
   7  Daemons.run_proc(
   8    'background_service', # name of daemon
   9  #  :dir_mode => :normal
  10  #  :dir => File.join(pwd, 'tmp/pids'), # directory where pid file will be stored
  11  #  :backtrace => true,
  12  #  :monitor => true,
  13    :log_output => true
  14  ) do
  15    exec "ruby #{file}"
  16  end

Change the file variable to point to the script you want to daemonize and your good to go.

You can now execute the daemon.rb script without parameters to get a list of available commands for controlling the daemon process:

   1  ERROR: no command given
   2  
   3  Usage: lib/background_service.rb <command> <options> -- <application options>
   4  
   5  * where <command> is one of:
   6    start         start an instance of the application
   7    stop          stop all instances of the application
   8    restart       stop all instances and restart them afterwards
   9    run           start the application and stay on top
  10    zap           set the application to a stopped state
  11  
  12  * and where <options> may contain several of the following:
  13  
  14      -t, --ontop                      Stay on top (does not daemonize)
  15      -f, --force                      Force operation
  16  
  17  Common options:
  18      -h, --help                       Show this message
  19          --version                    Show version

Simple example of how to use the named_scope feature:

   1  class Feed < ActiveRecord::Base
   2   
   3    named_scope :active, :conditions => "(active = 1)"
   4    named_scope :stale,  :conditions => ["last_updated > ?", 30.minutes.ago.to_s(:db)]

Usage:

   1  Feed.active # return the active feeds

Chaining is also possible:

   1  Feed.active.stale # return the feeds that need to be updated