Insert the current user id

I have made hook in this class – “class-donation-button-paypal-listner.php”

public function ipn_response_postmeta_handler($post_id, $posted) {

       foreach ($posted as $metakey => $metavalue) {
            update_post_meta($post_id, $metakey, $metavalue);
        }
        /* Start Custom Code */
           do_action('custom_after_do_payment', $post_id);
        /* End  Custom Code */
    }

under the custom code comment and wrote a function in mytheme file – “functions.php”

// Paypal Submit By
function callback_payment_submit_by($post_id){
	wp_update_post(array('ID' => $post_id, 'post_author' => get_current_user_id()));
}
add_action('custom_after_do_payment', 'callback_payment_submit_by');

Everything is run, but – ” get_current_user_id() ” function return 0 (Zero) value.

Thanks for your answer, i did it and it’s working.

Thanks,
Shubham