title: Compare updated_at in Rails
body: <pre><code>time_shift = DateTime.now - 75000
  @user.items.where(:updated_at &lt; time_shift) { |item|
  </code></pre>
  
  <p>I get error</p>
  
  <blockquote>
    <p>comparison of Symbol with DateTime
    failed</p>
  </blockquote>
  
  <p>Why and how to fix it?</p>
  
  <p>In model:</p>
  
  <pre><code>t.datetime "updated_at"
  </code></pre>