title: How to override default display values for a select field for foreign keys in the Django Admin?
body: <p>I'm creating models, where each model should be related with a user, like this:</p>
  <pre><code>class Item(models.Model):
      user = models.ForeignKey(User)
  </code></pre>
  <p>But then in the Django Admin, for an <code>Item</code>, it shows a <code>select</code> field with all the users listed by their usernames. In addition to their usernames, I also need to display each user's <code>first_name</code> and <code>last_name</code>.</p>
  <p>How can all three fields be displayed together within that select list in the Django Admin interface?</p>