title: Mongoose query a populated field
body: <pre><code>   db.History.find({'_file.project': 'someproject' )
        .populate('_file', 'name reference project')
        .sort(sortField || '-created')
        .limit(max || 64)
        .exec(this);
  </code></pre>
  
  <p>Here I'm trying to find all documents which match on a populated field from the _file reference. Is doesn't seem to work. Is something like this possible at all?</p>
  
  <p>I could duplicate the project field to this object, as a workaround just for querying but I'd rather not of course.</p>