title: Django query with related models
body: <p>For the below models:</p>
  
  <pre><code>class Customer(models.Model):
      id = models.IntegerField(primary_key=True)
  
  class OrderA(models.Model):
      name = models.CharField(max_length=20)
      foo = models.FloatField()
      customer = models.ForeignKey(Customer)
      type = models.IntegerField()
  
  class OrderB(models.Model):
      name = models.CharField(max_length=20)
      customer = models.ForeignKey(Customer)
      type = models.IntegerField()
  </code></pre>
  
  <p>I want to grab all the Customer objects with their related OrderA and OrderB objects in one go for a condition (where type in OrderA and OrderB equals 1) </p>