JezK
Edit File: gmk_functions.php
<?php function gmk_html($post) { $postMetaKeywords = get_post_meta($post->ID, '_gmk', true); ?> <style type="text/css"> input#gmk_field { width: 100%; padding: 10px 15px; } </style> <p><?php _e('Please add comma separated meta keywords to show for this content.', 'g-meta-keywords'); ?></p> <input name="gmk_field" id="gmk_field" type="text" value="<?= $postMetaKeywords ?>"> <?php } add_action('add_meta_boxes', 'gmk_add_custom_box'); function gmk_add_custom_box() { $post_type = trim(get_option('post_type')); $post_type = explode("\n", $post_type); $post_type = array_filter($post_type, 'trim'); $screens = ['post', 'page', 'category', 'tag', 'taxonomy', 'attachment', 'term', 'taxonomies']; foreach ($post_type as $line) { array_push($screens, $line); } foreach ($screens as $screen) { add_meta_box('gmk_box_id', 'G Meta Keywords', 'gmk_html', $screen); } } add_action('save_post', 'gmk_save_postdata'); function gmk_save_postdata($post_id) { if (array_key_exists('gmk_field', $_POST)) { update_post_meta($post_id, '_gmk', sanitize_text_field($_POST['gmk_field'])); } } require 'gmk_category_functions.php'; ?>