'username_exists'功能在Wordpress插件中不起作用

Question

I wanna use "username_exists" in my own plugin but when I use this function I got this error :

Fatal error: Uncaught Error: Call to undefined function get_user_by() in E:\xampp\htdocs\wordpress\wp-includes\user.php:1271 Stack trace: #0 E:\xampp\htdocs\wordpress\wp-content\pluginsegister-plus\index.php(86): username_exists('admin') #1 E:\xampp\htdocs\wordpress\wp-settings.php(255): include_once('E:\xampp\htdocs...') #2 E:\xampp\htdocs\wordpress\wp-config.php(89): require_once('E:\xampp\htdocs...') #3 E:\xampp\htdocs\wordpress\wp-load.php(37): require_once('E:\xampp\htdocs...') #4 E:\xampp\htdocs\wordpress\wp-blog-header.php(13): require_once('E:\xampp\htdocs...') #5 E:\xampp\htdocs\wordpress\index.php(17): require('E:\xampp\htdocs...') #6 {main} thrown in E:\xampp\htdocs\wordpress\wp-includes\user.php on line 1271

How can i fix it ?

Answer 1

I include 'pluggable.php' in my plugin and problem fixed

include_once(ABSPATH . 'wp-includes/pluggable.php');