title: Get all children models from a parent class - Django
body: <p>How can I get all the children models from a parent class?
  As an example I have :</p>
  
  <pre><code>class Device(PolymorphicModel):
     .....
  
  class Mobile(Device): 
     .....
  
  class Computer(Device):
     .....
  </code></pre>
  
  <p>So I want to get from the Device model its all descendants : Mobile, Computer as classes not as instances.</p>
  
  <p>Thank you.</p>