title: SQL Alchemy: Relationship with grandson
body: <p>I'm building a SQL Alchemy structure with three different levels of objects; for example, consider a simple database to store information about some blogs: there are some <code>Blog</code> object, some <code>Post</code> object and some <code>Comment</code> objects. Each <code>Post</code> belongs to a <code>Blog</code> and each <code>Comment</code> belongs to a <code>Post</code>. Using <code>backref</code> I can automatically have the list of all <code>Post</code>s belonging to a <code>Blog</code> and similarly for <code>Comment</code>s.</p>
  
  <p>I drafted a <a href="http://pastebin.com/dJgP9rNm" rel="nofollow">skeleton for such a structure</a>.</p>
  
  <p>What I would like to do now is to have directly in <code>Blog</code> an array of all the <code>Comment</code>s belonging to that <code>Blog</code>. I've tried a few approaches, but they don't work or even make SQL Alchemy cry in ways I can't fix. I'd think that mine is quite a frequent need, but I couldn't find anything helpful.</p>
  
  <p>Colud someone suggest me how to do that?</p>
  
  <p>Thanks.</p>