def update(self, request, *args, **kwargs):
        """Update the ``Relation`` object.

        Reject the update if user doesn't have ``EDIT`` permission on
        the collection referenced in the ``Relation``.
        """
        instance = self.get_object()
        if (not request.user.has_perm('edit_collection', instance.collection)
                and not request.user.is_superuser):
            return Response(status=status.HTTP_401_UNAUTHORIZED)

        return super().update(request, *args, **kwargs)
Update the ``Relation`` object.

        Reject the update if user doesn't have ``EDIT`` permission on
        the collection referenced in the ``Relation``.