title: Symfony2 / Twig dealing with getting URL query string values
body: <p>I'm trying to manipulate the query string values in a URL.</p>
  
  <p>I can get the current URL or route either from the Request object or Twig's functions, but it's the query string I'm struggling with.</p>
  
  <p>I don't need app.request.attributes.get('_route_params') as this gets the query string params that are in the route.</p>
  
  <p>I need to get query string params that are actually in the URL.</p>
  
  <p>I want to be able to do the two things listed below in both Symfony2 (in a PHP controller) and Twig (in a Twig template):</p>
  
  <ol>
  <li><p>Get all current query string values in the URL and display them</p></li>
  <li><p>Do 1, but change one of the query string values before displaying them </p></li>
  </ol>
  
  <p>I can't find anyone who knows how to do this.</p>