yii2 correct application architecture (pass data to layout) - php

Question

i need to send data from controllers to main layout (something like notifier of a new messages in top menu) i need it in all app(global)
i found one way to to pass variables to layout
Yii::$app->controller->myvar
from class property to layout, but i think it's not best way to duplicate code to all controllers, maybe i suppose to extend base Controller and set my logic here?
Tell me please the best practice to do what i want.
ps. Tnx and sorry for my English

Answer 1

In the controller, you can use
$this->view->params['name'] = 123
and in the layout
<?= $this->params['name'] ?>

Answer 2

1) You can use yii global app params
Yii::$app->params['foo'] = 'bar'; // controller
and
echo Yii::$app->params['foo']; // in view/layout/controllers/elsewhere
2) You can use session. Create a controller, that will be extended by others, with these 3 functions:
<?php
namespace common\components;
use Yii;
use yii\web\Controller;
class BaseController extends Controller
{
/**
* Set user flash notice
* #param $message
* #return mixed
*/
public function setFlash($key, $message){
return Yii::$app->session->setFlash($key, $message);
}
/**
* Has user flash notice
* #param $message
* #return mixed
*/
public function hasFlash($key){
if(Yii::$app->session->hasFlash($key)) return True;
else return false;
}
/**
* Get user flash notice
* #param $message
* #return mixed
*/
public function getFlash($key){
return Yii::$app->session->getFlash($key);
}
}
now in your controllers
use common\components\BaseController;
...
class MyController extends BaseController
...
$this->setFlash('foo','bar'); // setting flash var
and in your views
echo $this->context->getFlash('foo'); // getting flash var
or
echo Yii::$app->controller->getFlash('foo'); // getting flash var

Answer 3

The below line add in config\main.php
'user'=>array( 'class'=>'WebUser', // enable cookie-based authentication 'allowAutoLogin'=>true, ),
After that create new file in protected\components\WebUser.php, In this WebUser.php file
class WebUser extends CWebUser
{
private $_model;
function Update()
{
return $this->myvar='this is my variable';
}
}
You can access in layout file like this echo Yii::app()->user->update();