title: MongoEngine Dynamic Document
body: <p>I have a dynamicdocument model, and one of the fields I'm trying to set is called "index_this"</p>
  
  <p>I'm trying to set this field using dot notation:</p>
  
  <pre><code>In [17]: mongo_object.index_this = False
  
  In [18]: mongo_object.save()
  
  In [19]: mongo_object.index_this
  Out[19]: True
  </code></pre>
  
  <p>But as you can see, the save method doesn't to work.</p>
  
  <p>How are you supposed to save a single attribute when saving the model with a dynamic document?</p>