title: Get specific column from a collection ActiveRecord objects?
body: <p>How can I extract a list of IDs from a returned ActiveRecord results without re-querying the <code>ID</code> column alone?<br>
  For exmaple:</p>
  
  <pre><code>people = People.all
  people.get_ids #Returns an array of IDS  
  </code></pre>
  
  <p>My current solution is to loop through <code>people</code> and get the ID manually(which isn't very elegant, IMHO)  </p>