在function.php中通过php添加post id或slug

Question

i want to add custom field to post automatically so i have this code on theme function.php

add_action('publish_post', 'add_custom_field_automatically');

function add_custom_field_automatically($post_ID) {

global $wpdb;

if(!wp_is_post_revision($post_ID)) {

    add_post_meta($post_ID, 'test', 'text . $slug . text', true);

}

all works but value of custom field is plain text:
text . $slug . text

i want to be TEXT + id or slug of post + TEXT

so that variable $slug is not working and script add it as plain text

Answer 1

fixed by changing this line to

        add_post_meta($post_ID, 'test', "text '. $post_ID .' text", true);