title: How do I make an auto increment integer field in Django?
body: <p>I am making an <code>Order</code> model for a shopping cart and I need to make a field that auto increments when the order is made:</p>
  
  <pre><code>class Order(models.Model):
      cart = models.ForeignKey(Cart)
      add_date = models.DateTimeField(auto_now_add=True)
      order_number = models.IntegerField()
      enable = models.BooleanField(default=True)
  </code></pre>
  
  <p>How do I make the <code>IntegerField</code> auto increment?</p>