title: How to filter a query on the results of another one in django?
body: <p>Lets say that i have 2 models :</p>
  
  <pre><code>Class OrderEvent(models.Model):
      isPaid = models.Booleanfield()
  
  
  Class Participant(models.Model):
      orderEvent = models.ForeignKey(OrderEvent)
      participantFirstName = models.CharField()
      participantLastName = models.CharField()
      #etc...
  </code></pre>
  
  <p>And i want to get all the participants where Orderevent.isPaid = True.</p>
  
  <p>I think that i struggle to do something very simple...</p>