Call to a member function assign() on null

问题说明

ThinkPHP 报错 Fatal error: Call to a member function assign() on null in E:\xampp\htdocs\cms\thinkphp\library\think\Controller.php on line 161

class Article extends Controller {

    public function __construct() {
        echo 123;
    }

     public function index() {
         $this->assign('name','xiaoming');
         return view();
     }
 }

问题原因

父类中有一个构造函数，但是在当前构造函数中没有调用 parent::__construct(); 来实例化父类。

正确代码

class Article extends Controller {

    public function __construct() {
        parent::__construct();
        echo 123;
    }

    public function index() {
        $this->assign('name','xiaoming');
        return view();
    }
 }