Add "IsAccessibleForFree" to the Article schema

IsAccessibleForFree.php

<?php
/********* DO NOT COPY THE PARTS ABOVE THIS LINE *********/

/* 
 * Add the 'isAccessibleForFree' property to Yoast's Article schema.
 * Credit: Yoast team
 * Last Tested: Jun 24 2025 using Yoast SEO 25.3.1 on WordPress 6.8.1
 * Documentation: https://developer.yoast.com/features/schema/pieces/article/#api
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
 * DIFFERENT POST TYPES
 * Post: Change 123456 to the post ID
 * Page: Change is_single to is_page and 123456 to the page ID
 * Custom Post Type: Change is_single to is_singular and 123456 to the 'post_type_slug'
 * Example: is_singular( 'cpt_slug' )
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
 * MULTIPLE ITEMS
 * Multiple of the same type can use an array.
 * Example: is_single( array( 123456, 234567, 345678 ) )
 * Multiple of different types can repeat the if statement
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
 * @param array $data The Article schema data.
 * @return array The modified schema data.
*/

function add_is_accessible_for_free_to_article_schema($data ) {
	if ( is_single(6) ) { // Change to target the Accessible identifier
		$data['isAccessibleForFree']=true;
	}

	return $data;
}

add_filter('wpseo_schema_article', 'add_is_accessible_for_free_to_article_schema');