title: Django Model count in Foreign key
body: <p>I have two models.  </p>
  
  <pre><code>class Person(models.Model):
      first_name = models.CharField(max_length=50)
      last_name = models.CharField(max_length=50)
  
  class Position(models.Model):
      person = models.ForeignKey(Person)
      description = models.CharField(max_length=50)
  </code></pre>
  
  <p>Is there a way that i can count how many positions are there in this kind of Person model? Like Person.position.count..some sort of this. Please help me. This is counting inside model only. please.</p>