Bug to initialize a variable in the Laminas Session

I had a curious bug that happened in my code. I initialize a variable in the session in the controller. But when I retrieve the data in the view, the variable is equal to null.

The code of the Controller:

$session = new Container("exemple");
...
$session["data"] = "test";
//This line is the only way I found for the data to be initialized
$session["data"] = $session["data"];
...
return new ViewModel(array(
    "session" => $session
));

The code of the View:

$data = $this->session["data"];

I have to add the line below for my value to be initialized:

$session["data"] = $session["data"];

Without this line the variable is equal to NULL.

Why is it necessary to do this? Why is the variable not initialized without it?

Thanks for your help.

For using sessions in a Laminas controller, you have to do a few steps more than just initializing a session container without any detailed information about how this container should work.

As written in the official laminas documentation you have to define three things:

• a name for the session container
• a session storage handler
• an optional configuration for the session

As mentioned in the documentation using the reflection based approach might be the easiest approach. You have to define the session settings in config/autoload/global.config.php.

return [
    'session_containers' => [
        Laminas\Session\Container::class,
    ],
    'session_storage' => [
        'type' => Laminas\Session\Storage\SessionArrayStorage::class,
    ],
    'session_config'  => [
        'gc_maxlifetime' => 7200,
        // …
    ],
    // …
];

From now on you 're able to use the session in a controller. Think of something like the following code.

<?php

declare(strict_types=1);

namespace Marcel\Controller;

use Laminas\Mvc\Controller\AbstractActionController;
use Laminas\Session\Container as SessionContainer;

class YourController extends AbstractActionController
{
    public function __construct(
        protected readonly SessionContainer $sessionContainer
    ) {}
}

This controller has a constructor method, that injects the session container. Once injected, you can use the session in your controller. As written above, the session container will be injected via reflection based approach. You have to define a controller factory in your module config.

<?php

declare(strict_types=1);

namespace Marcel;

use Laminas\ServiceManager\AbstractFactory\ReflectionBasedAbstractFactory;

return [
    'controllers' => [
        'factories' => [
            // Add this line
            Controller\YourController::class => ReflectionBasedAbstractFactory::class,
        ],
    ],
    // …
];

From now on your controller will be initialized with a valid session container as you have it defined in your global config. You can use it as follows ...

// setting session data
public function indexAction()
{
    $this->sessionContainer->data = 'Some random data';

    return [];
}

// reading session data
public function addAction()
{
    return [
        'data' => $this->sessionContainer->data ?? null,
    ];
}

In your view you have to use the name of the defined variable data and not the session container itself.