snapshot.py

class Snapshot(models.Model):
  # unique identifier for snapshots
  id = models.Charfield(max_length=32)
  # the record which initiated the snapshot
  root_id = models.CharField(max_length=32)

  @transaction.atomic
  def restore(self):
    [x.restore() for x in self.snapshot_records.all()]
    self.delete()
    
class SnapshotRecord(models.Model)
  snapshot = models.ForeignKey(Snapshot, null=False)
  # this field is used to represent the record affected by the delete
  record_id = models.CharField(max_length=32)
  # these fields are used to represent links to another record.
  # if they are set, it means a
  fk_field = models.CharField(max_length=64, null=True)
  fk_value = models.CharField(max_length=64, null=True)

  @transaction.atomic
  def restore(self):
    # we'll implement BaseModel.get later
    record = BaseModel.get(self.record_id, include_deleted=True)
    
    if fk_model is None:
      record.is_deleted = False
    else:
      setattr(record, self.fk_field, self.fk_value)
    record.save()
    self.delete()