protected function getResolverRegistry() {
// Tell GraphQL how to resolve types of a common interface.
$registry->addTypeResolver('NodeInterface', function ($value) {
if ($value instanceof NodeInterface) {
switch ($value->bundle()) {
case 'article': return 'Article';
case 'page': return 'Page';
throw new Error('Could not resolve content type.');
$registry->addFieldResolver('Query', 'route', $builder->compose(
$builder->produce('route_load')
->map('path', $builder->fromArgument('path')),
$builder->produce('route_entity')
->map('url', $builder->fromParent())