title: How update only the children calling save in hierarchy?
body: <p>I have the following model:</p>
  
  <pre><code>class Mother(models.Model):
      created_at = models.DateTimeField()
  
  class Father(Mother):
      default = models.BooleanField()
  
      def save(self, *args, **kwargs):
          if self.default:
              Father.objects.update(default=False)
          super(Father, self).save(*args, **kwargs)
  
  class ChildOne(Father):
      a_attribute = models.AttributeField()
  
  class ChildTwo(Father):
      b_attribute = models.AttributeField()
  </code></pre>
  
  <p>If I call <code>childtwo.save()</code>, how do I make sure all <code>childone</code> do not get updated? Is it possibly to modify the save method in Father's class to distinguish between the children calling <code>save()</code>? I mean, without overriding <code>Father</code>'s save method in all classes I inherent it.</p>