Yii::app()->user->id sometimes gives empty result - php

Question

Hosted on Heroku
Yii 1.14
PHP 5.6
A stranger error when Yii::app()->user->id returns the id sometimes but at other times returns empty. The same page load results in this strange behaviour.
I check for this in a parent class called AdminController.php
class AdminController extends CController
{
public $partnerCount;
public $vendorCount;
public $plantationMarkers;
public function init()
{
echo Yii::app()->user->id;
if(empty(Yii::app()->user->id)) {
echo 'User id empty: '. Yii::app()->user->id;
//$this->redirect(Yii::app()->createAbsoluteUrl('admin/auth/login'));
exit;
return false;
}
elseif(!Yii::app()->user->checkAccess(User::PARTNER)) {
$this->layout = 'column1';
$this->render('/auth/not-authorized');
return false;
}
$this->partnerCount = $this->getPartnerCount();
$this->vendorCount = $this->getVendorCount();
$this->plantationMarkers = $this->getPlantationMarkers();
return true;
}
So in this code 'User id empty: ' is echoed in some cases while in other cases I get the id.
The point is with no change in code how can this work at some time while not at other times.

Answer 1

Solved by changing the session to be stored in DB table. I am not sure but there was some issue with Yii storing session on the server under Heroku.
The change is required in the config array under 'components'.
From :
'session' => array(
'class' => 'CHttpSession',
'timeout' => 2400,
'cookieParams' => array(
'httpOnly' => true,
'secure' => false,
),
),
To :
'session' => array(
'timeout' => 2400,
'cookieParams' => array(
'httpOnly' => true,
'secure' => false,
),
'class' => 'CDbHttpSession',
'connectionID' => 'db',
'sessionTableName' => 'lig_session',
),