Blank Session ID in Module's BeforAction

[mtangoo]

I have something like below and I get empty session id unless I add session_start() before getting ID
Is this by design or a bug?

class Module extends \yii\base\Module 
{    
    public function beforeAction($action)
    {
        if (parent::beforeAction($action)) 
        {    
            //session_start(); I have to uncomment it for session to work
            $sid = Yii::$app->session->id
            return true;
        }
        else
            return false;
    } 
 } 

[qiangxue]

You have to start the session first Yii::$app->session->open().

[mtangoo]

Why is that? is there any way to automate session open() like we do in database component?

[dynasource]

starting a session goes at cost of performance

[qiangxue]

When you try to access session data, the session will be started automatically. For this session ID access, it will not do so because it is possible you want to check session ID before it is started.

[mtangoo]

so where session get started in module for example? AfterAction?

[qiangxue]

You can do it in module's init() method if you want to force starting session for every module request.