Plugin for creating a post type with a custom API that reflects Schema.org data structures

schema-api.php

<?php

/*
 * Plugin Name: Schema API
 * Plugin URI:
 * Description:
 * Version: 0.1.0
 * Author: Micah Wood
 * Author URI:  https://wpscholar.com
 * License:     GPL2
 * License URI: https://www.gnu.org/licenses/gpl-2.0.html
 * Text Domain:
 */

add_action( 'init', function () {

	register_post_type( 'person', [
		'public'   => true,
		'labels'   => [
			'name'          => 'People',
			'singular_name' => 'Person',
		],
		'supports' => [
			'title',
			'editor',
			'custom-fields',
			'postal-address',
		],
	] );

} );

add_action( 'rest_api_init', function () {

	register_rest_route( 'schema/v1', '/people', [
		'methods'  => 'GET',
		'callback' => function ( WP_REST_Request $request ) {
			$query = new WP_Query( [
				'post_type' => 'person',
			] );

			$posts = (array) $query->posts;

			return rest_ensure_response( array_map( 'transformPost', $posts ) );
		},
		'args'     => array(),
	] );

	register_rest_route( 'schema/v1', '/person/(?P<id>\d+)', [
		'methods'  => 'GET',
		'callback' => function ( WP_REST_Request $request ) {
			return rest_ensure_response( transformPost( get_post( $request->get_param( 'id' ) ) ) );
		},
		'args'     => array(
			'id' => array(
				'validate_callback' => function ( $param, $request, $key ) {
					if ( ! is_numeric( $param ) ) {
						return new WP_Error( 'bad_post_id', __( 'Invalid post ID format. Please pass an integer.' ), array( 'status' => 400 ) );
					}
					$post_id = (int) $param;
					if ( false === get_post_status( $post_id ) || 'person' !== get_post_type( $post_id ) ) {
						return new WP_Error( 'bad_post_id', __( 'Invalid post ID.' ), array( 'status' => 400 ) );
					}

					return true;
				}
			),
		),
	] );

} );

function transformPost( WP_Post $post ) {
	$obj = new stdClass();

	$obj->givenName = $post->first_name;
	$obj->familyName = $post->last_name;
	$obj->postalAddress = extractAddress( $post );

	return $obj;
}

function extractAddress( WP_Post $post ) {
	return (object) array_filter( [
		'addressCountry'      => $post->addressCountry,
		'addressLocality'     => $post->addressLocality,
		'addressRegion'       => $post->addressRegion,
		'postOfficeBoxNumber' => $post->postOfficeBoxNumber,
		'postalCode'          => $post->postalCode,
		'streetAddress'       => $post->streetAddress,
	] );
}

/*

*/