wp-graphql-popular-posts-connection.php

add_action( 'graphql_register_types', function() {

	register_graphql_connection([
		'fromType' => 'RootQuery',
		'toType' => 'Post',
		'fromFieldName' => 'popularPosts',
		'connectionTypeName' => 'RootQueryToPopularPostsConnection',
		'resolve' => function( $root, $args, \WPGraphQL\AppContext $context, $info ) {

			$resolver = new \WPGraphQL\Data\Connection\PostObjectConnectionResolver( $root, $args, $context, $info );

			// Get the query amount from the resolver.
			// This takes into account the arguments for `first` and `last` on the connection
			// and determines how many items to ask for
			$per_page = $resolver->get_query_amount();

			// Query for the popular posts. It's important to JUST get the ids
			$popular_post_ids = new WP_Query( [
				'posts_per_page' => $per_page,
				'meta_key' => 'wpb_post_views_count',
				'orderby' => 'meta_value_num',
				'order' => 'DESC',
				'fields' => 'ids', // <-- Just ask for the IDs. WPGraphQL connection resolver will get the full objects for you
				'no_found_rows' => true,
			] );

			// If there are no popular posts, return null for the connection
			if ( empty( $popular_post_ids->posts ) ) {
				return null;
			}

			$resolver->set_query_arg( 'post__in', $popular_post_ids->posts );
			return $resolver->get_connection();
		}
	]);

} );