yii2 如何開啟session

use??yiiwebSession; ? $session?=?Yii::$app->session; //?check?if?a?session?is?already?open if?($session->isActive)?... //?open?a?session $session->open(); //?close?a?session $session->close(); //?destroys?all?data?registered?to?a?session. $session->destroy();

$session?=?Yii::$app->session; $session->set('user_id',?'1234'); //OR $session['user_id']?=?'1234'; //OR $_SESSION['user_id']?=?'1234';

$session?=?Yii::$app->session; $user_id?=?$session->get('user_id'); //OR $user_id?=?$session['user_id']; //OR $user_id?=?isset($_SESSION['user_id'])???$_SESSION['user_id']?:?null;

$session?=?Yii::$app->session; $session->remove('user_id'); //OR unset($session['user_id']); //OR unset($_SESSION['user_id']);