Books WordPress REST API Example

books-cpt-metabox.php

<?php
function register_books_cpt() {

	$args = array(
		'labels'          => array(
			'name'          => _x( 'Books', 'post type general name' ),
			'singular_name' => _x( 'Book', 'post type singular name' ),
		),
		'description'     => '',
		'hierarchical'    => false,
		'menu_position'   => null,
		// No admin UI or archive pages
		'public'          => true,
		// Expose through REST API
		'show_in_rest'    => true,
		'rest_base'       => 'books',
		'capability_type' => 'post',
		'supports'        => array( 'title', 'editor', 'custom-fields' )
	);
	register_post_type( 'books', $args );
}

add_action( 'init', 'register_books_cpt' );

function add_book_info_metabox() {
	add_meta_box( 'book-info-meta-box', 'Book Info', 'book_info_metabox_markup', 'books', 'advanced', 'high', null );
}

add_action( 'add_meta_boxes', 'add_book_info_metabox' );

function book_info_metabox_markup( $object ) {
	wp_nonce_field( basename( __FILE__ ), 'book-info-meta-box-nonce' );

	?>
	<div>
		<label for='_book_rating'>Book Rating</label>
		<select name='_book_rating'>
			<?php
			$option_values = array( 0, 1, 2, 3, 4, 5 );

			foreach ( $option_values as $key => $value ) {
				if ( $value == get_post_meta( $object->ID, '_book_rating', true ) ) {
					?>
					<option selected><?php echo $value; ?></option>
					<?php
				} else {
					?>
					<option><?php echo $value; ?></option>
					<?php
				}
			}
			?>
		</select>
	</div>
	<?php
}

function save_book_info_metabox( $post_id, $post, $update ) {
	if ( ! isset( $_POST['book-info-meta-box-nonce'] ) || ! wp_verify_nonce( $_POST['book-info-meta-box-nonce'], basename( __FILE__ ) ) ) {
		return $post_id;
	}

	if ( ! current_user_can( 'edit_post', $post_id ) ) {
		return $post_id;
	}

	if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
		return $post_id;
	}

	if ( 'books' != $post->post_type ) {
		return $post_id;
	}

	$book_rating = '';

	if ( isset( $_POST['_book_rating'] ) ) {
		$book_rating = (int) $_POST['_book_rating'];
	}
	update_post_meta( $post_id, '_book_rating', $book_rating );

}

add_action( 'save_post', 'save_book_info_metabox', 10, 3 );

books-detail-endpoint.php

<?php
function book_details( $request ) {
	$post_id = (int) $request['id'];


	$rating = get_post_meta( $post_id, '_book_rating', true );
	$rating = ( empty( $rating ) ) ? false : (int) $rating;

	$thumbnail = get_post_thumbnail_id( $post_id );
	if ( empty( $thumbnail ) ) {
		$thumbnail = false;
	} else {
		$thumbnail = wp_get_attachment_image_src( $thumbnail, 'thumbnail' );
		if ( is_array( $thumbnail ) ) {
			$thumbnail = array(
				'src'    => $thumbnail[0],
				'width'  => $thumbnail[1],
				'height' => $thumbnail[2],
			);
		}
	}

	global $post;
	$post = get_post( $post_id );
	setup_postdata( $post );

	if ( null !== $post ) {
		$return = array(
			'ID'        => $post_id,
			'title'     => get_the_title(),
			'thumbnail' => $thumbnail,
			'rating'    => $rating,
			'content'   => get_the_content(),
		);

		wp_reset_postdata( $post );
	}

	$response = new WP_REST_Response( $return );

	$response->header( 'Access-Control-Allow-Origin', apply_filters( 'access_control_allow_origin', '*' ) );
	$response->header( 'Cache-Control', 'max-age=' . apply_filters( 'api_max_age', WEEK_IN_SECONDS ) );

	return $response;
}

books-list-endpoints.php

<?php
function list_books( $request ) {

	$args = $request['query_args'];

	$book_args = array(
		'post_type'           => 'books',
		'post_status'         => 'publish',
		'posts_per_page'      => 25,
		'ignore_sticky_posts' => true,
	);

	$standard_params = array(
		'order',
		'orderby',
		'author',
		'post_type',
		'ignore_sticky_posts',
		'paged',
		'page',
		'nopaging',
		'posts_per_page',
		's',
	);

	foreach ( $standard_params as $standard_param ) {
		if ( isset( $args[ $standard_param ] ) && ! empty( $args[ $standard_param ] ) ) {
			$book_args[ $standard_param ] = $args[ $standard_param ];
		}
	}

	$the_query = new WP_Query( $book_args );

	$return = array(
		'total'          => (int) $the_query->found_posts,
		'count'          => (int) $the_query->post_count,
		'pages'          => (int) $the_query->max_num_pages,
		'posts_per_page' => (int) $book_args['posts_per_page'],
		'query_args'     => $book_args,
		'books'          => array(),
	);

	if ( $the_query->have_posts() ):

		$i = 0;

		while ( $the_query->have_posts() ):
			$the_query->the_post();
			$post_id = get_the_ID();

			$rating = get_post_meta( $post_id, '_book_rating', true );
			$rating = ( empty( $rating ) ) ? false : (int) $rating;

			$thumbnail = get_post_thumbnail_id( $post_id );
			if ( empty( $thumbnail ) ) {
				$thumbnail = false;
			} else {
				$thumbnail = wp_get_attachment_image_src( $thumbnail, 'thumbnail' );
				if ( is_array( $thumbnail ) ) {
					$thumbnail = array(
						'src'    => $thumbnail[0],
						'width'  => $thumbnail[1],
						'height' => $thumbnail[2],
					);
				}
			}

			$return['books'][ $i ] = array(
				'ID'        => $post_id,
				'title'     => get_the_title( $post_id ),
				'rating'    => $rating,
				'thumbnail' => $thumbnail,
			);

			$i ++;

		endwhile;

		wp_reset_postdata();

	endif;


	$response = new WP_REST_Response( $return );

	$response->header( 'Access-Control-Allow-Origin', apply_filters( 'access_control_allow_origin', '*' ) );
	$response->header( 'Cache-Control', 'max-age=' . apply_filters( 'api_max_age', WEEK_IN_SECONDS ) );

	return $response;
}

books-register-rating-rest-field.php

<?php
function register_books_rest_fields() {
	register_rest_field(
		'books',
		'rating',
		array(
			'get_callback'    => function ( $data ) {
				return (int) get_post_meta( $data['id'], '_book_rating', true );
			},
			'update_callback' => function ( $value, $post ) {
				$value = intval( $value );
				if ( $value >= 0 && $value <= 5 ) {
					update_post_meta( $post->ID, '_book_rating', $value );
				}
			},
			'schema'          => array(
				'description' => __( 'The rating, 0 - 5, for the book.' ),
				'type'        => 'integer'
			),
		)
	);
}

add_action( 'rest_api_init', 'register_books_rest_fields' );

books-register-rest-routes.php

<?php
function register_books_rest_routes() {

	register_rest_route( 'app/v1', '/books', array(
		'methods'  => 'GET',
		'callback' => 'list_books',
		'args'     => array(
			'query_args' => array(
				'default' => array(),
			),
		),
	) );

	register_rest_route( 'app/v1', '/books/(?P<id>\d+)', array(
		'methods'  => 'GET',
		'callback' => 'book_details',
		'args'     => array(
			'id' => array(
				'validate_callback' => function ( $param, $request, $key ) {
					if( ! is_numeric( $param ) ){
						return new WP_Error( 'books_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 ) || 'books' !== get_post_type( $post_id ) ) {
						return new WP_Error( 'books_bad_post_id', __( 'Invalid books post ID.' ), array( 'status' => 400 ) );
					}
					return true;
				}
			),
		),
	) );

}

add_action( 'rest_api_init', 'register_books_rest_routes' );