title: doctrine: setting association with id instead of object instance
body: <p>is it possible to set associations between two objects, for example <code>article</code> and <code>comment</code> like this:</p>
  
  <pre><code>comment.setArticle(10) // 10 is the id of article
  </code></pre>
  
  <p>autogenerated setArtcicle methods takes as argument object Article of course but maybe there are some tricks to do this?</p>
  
  <p>It is very important to me from performance point of view - i would like to avoid making SQL calls always when I want to set an association. In my case there will be plenty of such unnecessary queries.</p>