def METHOD_NAME(self, request, *args, **kwargs):
    instance = self.get_object()
    serializer = self.get_serializer(
        instance=instance,
        data=request.data
    )
    serializer.is_valid(raise_exception=True)
    repos = set(serializer.validated_data['repositories_followed']) ^ \
        set(instance.repositories_followed.all())
    authors = set(serializer.validated_data['namespaces_followed']) ^ \
        set(instance.namespaces_followed.all())
    serializer.save()
    for repo in repos:
        count = models.UserPreferences.objects.filter(
            repositories_followed=repo).count()
        name = repo.provider_namespace.namespace.name
        fields = {
            'content_name': '{}.{}'.format(name, repo.name),
            'content_id': repo.id,
            'follower_count': count,
        }
        serializers.influx_insert_internal({
            'measurement': 'content_follower',
            'fields': fields
        })
    for author in authors:
        count = models.UserPreferences.objects.filter(
            namespaces_followed=author).count()
        fields = {
            'author_name': author.name,
            'author_id': author.id,
            'follower_count': count,
        }
        serializers.influx_insert_internal({
            'measurement': 'author_follower',
            'fields': fields
        })
    return Response(serializer.data)