title: Ruby, Rails and difference between two dates
body: <p>I will let the example speak for it self:</p>
  
  <pre><code>ruby-1.9.2-p0 &gt;   DateTime.now
   =&gt; Mon, 14 Feb 2011 20:02:49 +0100 
  ruby-1.9.2-p0 &gt; User.first.created_at
   =&gt; Tue, 04 May 2010 07:03:24 CEST +02:00 
  ruby-1.9.2-p0 &gt; DateTime.now-User.first.created_at
  TypeError: expected numeric or date
      from /Users/Jacob/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/date.rb:1356:in `-'
      from /Users/Jacob/.rvm/gems/ruby-1.9.2-p0@loyaltric_template/gems/activesupport-3.0.3/lib/active_support/core_ext/date/calculations.rb:98:in `minus_with_duration'
      from (irb):47
      from /Users/Jacob/.rvm/gems/ruby-1.9.2-p0@loyaltric_template/gems/railties-3.0.3/lib/rails/commands/console.rb:44:in `start'
      from /Users/Jacob/.rvm/gems/ruby-1.9.2-p0@loyaltric_template/gems/railties-3.0.3/lib/rails/commands/console.rb:8:in `start'
      from /Users/Jacob/.rvm/gems/ruby-1.9.2-p0@loyaltric_template/gems/railties-3.0.3/lib/rails/commands.rb:23:in `&lt;top (required)&gt;'
      from script/rails:6:in `require'
      from script/rails:6:in `&lt;main&gt;'
  ruby-1.9.2-p0 &gt; 
  </code></pre>
  
  <p>What?!?</p>