Django ModelChoiceField optgroup tag

You don’t need to create any custom field, Django already does the job, just pass the choices well formatted:

MEDIA_CHOICES = (
 ('Audio', (
   ('vinyl', 'Vinyl'),
   ('cd', 'CD'),
  )
 ),
 ('Video', (
   ('vhs', 'VHS Tape'),
   ('dvd', 'DVD'),
  )
 ),
)