text: from django.db import models
  
  from django_evolution.mutations import AddField, SQLMutation
  
  
  MUTATIONS = [
      AddField('ReviewRequest', 'shipit_count', models.IntegerField, initial=0,
               null=True),
      SQLMutation('populate_shipit_count', ["""
          UPDATE reviews_reviewrequest
             SET shipit_count = (
                 SELECT COUNT(*)
                   FROM reviews_review
                  WHERE reviews_review.review_request_id =
                        reviews_reviewrequest.id
                    AND reviews_review.public
                    AND reviews_review.ship_it
                    AND reviews_review.base_reply_to_id is NULL)
  """])
  ]
  