Register attachments connection for posts

post-attachments-connection.php

add_action( 'graphql_register_types', function() {

	register_graphql_connection([
		'fromType' => 'Post',
		'toType' => 'MediaItem',
		'fromFieldName' => 'attachments',
		'resolveNode' => function( $id, $args, $context ) {
			return \WPGraphQL\Data\DataSource::resolve_post_object( $id, $context );
		},
		'resolve' => function( $post, $args, $context, $info ) {
			$resolver = new \WPGraphQL\Data\Connection\PostObjectConnectionResolver( $post, $args, $context, $info, 'attachment' );
			$resolver->setQueryArg( 'post__parent', $post->ID );
			return $resolver->get_connection();
		}
	]);

} );