Migrate from old style tree with parent id to django-mptt or Treebeard's nested sets

gistfile1.py

from itertools import count


def migrate_children(tree_id, node, counter):
    for index, child in enumerate(Region.objects.filter(parent=node).order_by('name')):
        child.tree_id = tree_id
        child.lft = counter.next()
        migrate_children(tree_id, child, counter)
        child.rgt = counter.next()
        child.save()

for index, node in enumerate(Region.objects.filter(depth=1).order_by('name')):
    counter = count(1)
    node.tree_id = index
    node.lft = counter.next()
    migrate_children(index, node, counter)
    node.rgt = counter.next()
    node.save()