Slim php - access container from middleware - php

Question

I am trying to access the $container from my middleware, but i am not getting much luck.
In my index.php file I have
require '../../vendor/autoload.php';
include '../bootstrap.php';
use somename\Middleware\Authentication as Authentication;
$app = new \Slim\App();
$container = $app->getContainer();
$app->add(new Authentication());
And then I have a class Authentication.php like this
namespace somename\Middleware;
class Authentication {
public function __invoke($request, $response, $next) {
$this->logger->addInfo('Hi from Authentication middleware');
but i get an error
Undefined property: somename\Middleware\Authentication::$logger in ***
I have also tried adding the following constructor to the class but I also get no joy.
private $container;
public function __construct($container) {
$this->container = $container;
}
Could anyone help please?

Answer 1

Best Practice to Middleware Implementation is Something like this :
Place this code inside your dependency section :
$app = new \Slim\App();
$container = $app->getContainer();
/** Container will be passed to your function automatically **/
$container['MyAuthenticator'] = function($c) {
return new somename\Middleware\Authentication($c);
};
then inside your Authentication class create constructor function like you mentioned :
namespace somename\Middleware;
class Authentication {
protected $container;
public function __invoke($request, $response, $next)
{
$this->container->logger->addInfo('Hi from Authentication middleware');
}
public function __construct($container) {
$this->container = $container;
}
/** Optional : Add __get magic method to easily use container
dependencies
without using the container name in code
so this code :
$this->container->logger->addInfo('Hi from Authentication middleware');
will be this :
$this->logger->addInfo('Hi from Authentication middleware');
**/
public function __get($property)
{
if ($this->container->{$property}) {
return $this->container->{$property};
}
}
}
After inside your index.php add Middleware using name resolution like this:
$app->add('MyAuthenticator');

Answer 2

I disagree with Ali Kaviani's Answer. When adding this PHP __magic function (__get), the code will be a lot more difficult to test.
All the required dependencies should be specified on the constructor.
The benefit is, that you can easily see what dependencies a class has and therefore only need to mock these classes in unit-tests, otherwise you would've to create a container in every test. Also Keep It Simple Stupid
I'll show that on the logger example:
class Authentication {
private $logger;
public function __construct($logger) {
$this->logger = $logger;
}
public function __invoke($request, $response, $next) {
$this->logger->addInfo('Hi from Authentication middleware');
}
}
Then add the middleware with the logger parameter to the container:
$app = new \Slim\App();
$container = $app->getContainer();
$container['MyAuthenticator'] = function($c) {
return new somename\Middleware\Authentication($c['logger']);
};
Note: the above registration to the container could be done automatically with using PHP-DI Slim (but that should be also slower).