title: MongoEngine - Query Operator for "contains" - Check if value is in list
body: <p>I have a MongoDB <code>ListField()</code> of IDs and need to check in a query if a certain ID is in this list. </p>
  
  <p>Usually I do it the other way round: I check if a value is in a list.</p>
  
  <pre><code>MyClass.objects.filter(id__in=id_list)
  </code></pre>
  
  <p>I tried to use the "contains" query operator but it seems to work only for strings.</p>
  
  <p>So, does anybody know how to achieve this?</p>
  
  <p>Thanks :)</p>