title: Django query negation
body: <p>I know how to build filters and Q objects in django, but I don't know how to negate the operators that the API provides, for example for the contains operator I would like something like notcontains.</p>
  
  <p>e.g. </p>
  
  <pre><code>q=Q(name__notcontains="SomeString")
  </code></pre>
  
  <p>This would get me all objects whose name do not contain "SomeString".</p>
  
  <p>Is there some syntax that I'm missing?</p>
  
  <p>Thankyou.</p>