title: Editing the values while changing Django model field type
body: <p>I have a field in my Django model:</p>
  
  <p><code>state = models.BooleanField(default=False)</code></p>
  
  <p>I want to change the field type to:</p>
  
  <pre><code>STATUS_CHOICES = (
      (Enabled, 'Enabled'),
      (Disabled, 'Disabled'),
      (PENDING, 'Pending'),
  )
  models.CharField(max_length=8, choices=STATUS_CHOICES, default=Pending)
  </code></pre>
  
  <p>Currently there is content in my model table with boolean values (<code>1</code> or <code>0</code>).
  How can I migrate this change and also transforming the existing values <code>1</code> to <code>Enabled</code> and <code>0</code> to <code>Disabled</code>?</p>