WP_REST_Meta_Fields

15#[AllowDynamicProperties]16abstract class WP_REST_Meta_Fields {17 18	/**19	 * Retrieves the object meta type.20	 *21	 * @since 4.7.022	 *23	 * @return string One of 'post', 'comment', 'term', 'user', or anything24	 *                else supported by `_get_meta_table()`.25	 */26	abstract protected function get_meta_type();27 28	/**29	 * Retrieves the object meta subtype.30	 *31	 * @since 4.9.832	 *33	 * @return string Subtype for the meta type, or empty string if no specific subtype.34	 */35	protected function get_meta_subtype() {36		return '';37	}38 39	/**40	 * Retrieves the object type for register_rest_field().41	 *42	 * @since 4.7.043	 *44	 * @return string The REST field type, such as post type name, taxonomy name, 'comment', or `user`.45	 */46	abstract protected function get_rest_field_type();47 48	/**49	 * Registers the meta field.50	 *51	 * @since 4.7.052	 * @deprecated 5.6.053	 *54	 * @see register_rest_field()55	 */56	public function register_field() {57		_deprecated_function( __METHOD__, '5.6.0' );58 59		register_rest_field(60			$this->get_rest_field_type(),61			'meta',62			array(63				'get_callback'    => array( $this, 'get_value' ),64				'update_callback' => array( $this, 'update_value' ),65				'schema'          => $this->get_field_schema(),66			)67		);68	}69 70	/**71	 * Retrieves the meta field value.72	 *73	 * @since 4.7.074	 *75	 * @param int             $object_id Object ID to fetch meta for.76	 * @param WP_REST_Request $request   Full details about the request.77	 * @return array Array containing the meta values keyed by name.78	 */79	public function get_value( $object_id, $request ) {80		$fields   = $this->get_registered_fields();81		$response = array();82 83		foreach ( $fields as $meta_key => $args ) {84			$name       = $args['name'];85			$all_values = get_metadata( $this->get_meta_type(), $object_id, $meta_key, false );86 87			if ( $args['single'] ) {88				if ( empty( $all_values ) ) {89					$value = $args['schema']['default'];90				} else {91					$value = $all_values[0];92				}93 94				$value = $this->prepare_value_for_response( $value, $request, $args );