title: How do I query objects of all children of a node with Django mptt?
body: <p>I am trying to get the objects of all the children of a given node on Django with django-mppt</p>
  
  <p>I have a model designed as shown below, the classes/categories (node) with the same indent level defines siblings, inner indents are children. The objects tagged with a category are shown just below the category (node). The objects start with a <code>-</code> symbol. The numbers along the classes/categories (nodes) are the ids.</p>
  
  <p>all the nodes are the instances of <code>Category</code> class with the <code>id</code> given.</p>
  
  <pre><code>high school (1)
      class 8 (2)
          division a (3)
              -Billie
              -Tre
              -Mike
  
          division b (4)
              -Patrik
              -Pete
              -Andy
      class 9 (3)
          division a (8)
              -Mark
              -Tom
              -Travis
  
          division b (5)
              -Gerard
              -Frank
              -Mikey
  
      class 10  (4)
          division a (6)
              -Hayley
              -Jeremy
              -Taylor
  
          division b (7)
              -Steven
              -Slash
              -Izzy
  </code></pre>
  
  <p>I can get the query sets of a specific node this way,</p>
  
  <pre><code>&gt;&gt;&gt; Category.objects.get(pk=7).product_set.all()
  [Steven, Slash, Izzy]
  
  
  &gt;&gt;&gt; Category.objects.get(pk=4).product_set.all()
  [Mark, Tom, Travis]
  </code></pre>
  
  <p>How do I query with <code>pk=1</code>, <code>pk=2</code>, <code>pk=3</code> or <code>pk=4</code> to get all the child objects?</p>
  
  <p>example,</p>
  
  <p>the query for <code>pk=2</code> query must return</p>
  
  <pre><code>[Billie, Tre, Mike, Patrik, Pete, Andy]
  </code></pre>