Wordpress Relevanssi search plugin with Oshin theme

relevanssi-oshin.php

/* Additional content from Oshin page builder is not indexed with the Relevanssi search plugin
 * The Oshin page builder stores it's content in the 'wp_postmeta' table
 * The function adds this content to the relevanssi index
 * 
 * Oshin: 3.1 (http://brandexponents.com/oshin/)
 * Relevanssi: 3.5.2 (http://www.relevanssi.com/)
*/

function add_extra_content($content, $post) {
    global $wpdb;
    $content = $wpdb->get_var("SELECT meta_value FROM wp_postmeta WHERE post_id = $post->ID AND meta_key = '_be_pb_content'");
    
    return $content;
}
add_filter('relevanssi_content_to_index', 'add_extra_content', 10, 2);