# Middleware and DI with PHP-DI/Slim-Bridge

**URL:** https://discourse.slimframework.com/t/middleware-and-di-with-php-di-slim-bridge/91
**Category:** Questions
**Created:** [April 6, 2016, 10:16am UTC](https://discourse.slimframework.com/t/middleware-and-di-with-php-di-slim-bridge/91 "2016-04-06T10:16:35Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![nisbeti](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.slimframework.com/nisbeti/32/206_2.png) [@nisbeti](https://discourse.slimframework.com/u/nisbeti)
#### Post date: [April 6, 2016, 10:16am UTC](https://discourse.slimframework.com/t/middleware-and-di-with-php-di-slim-bridge/91/1 "2016-04-06T10:16:35Z")

</div>

I had the following problem with PHP-DI/Slim-Bridge, so I thought I’d shar it and the answer that I recieved:

I am using PHP-DI/Slim-Bridge in a Slim3 app. I am using _Autowiring_ for the Controllers, so my definitions looks like this:

```php
use App\Interfaces\FlashInterface;
use App\Helpers\Flash;

  $definitions = [
 
    FlashInterface::class => function () {
      return new Flash;
    },
  
  ]

```

Then my route is:

```php
  $app->get('/auth/register', ['\App\Controllers\Auth\Register', 'getRegister'])->setName('auth.register')->add($guest);

```

My controller is:

```php
namespace App\Controllers\Auth;

use App\Auth\Auth;

use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;
use App\Interfaces\FlashInterface as Flash;
use Slim\Views\Twig as View;

class Register
{
    public function getRegister(Request $request, Response $response, View $view, Flash $flash)
    {
        return $view->render($response, 'auth/register.twig');
    }
    

```

All this is fine, except that I want the `guest` middleware to also use _Autowiring_:

```php
use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;
use App\Interfaces\FlashInterface as Flash;
use App\Interfaces\AuthInterface as Auth;

$guest = function (Request $request, Response $response, $next, Flash $flash, Auth $auth) {
    if ($auth) {
        $flash->addMessage('warning', 'You need to be logged out to see this page');
        return $response->withRedirect($this->get('router')->pathFor('home'));
    }
    $response = $next($request, $response);
    return $response;
};

```

So, I was hoping that this would inject the TypeHinted `$flash` object into the Middleware closure, but it doesn’t. The script fails as `$flash` is `null`.  
Instead I have to define an additional static `flash` object in my container:

```php
use App\Interfaces\FlashInterface;
use App\Helpers\Flash;

  $definitions = [
 
    FlashInterface::class => function () {
      return new Flash;
    },
    
    'flash' => function () {
        return new Flash;
    },

  ]

```

Then get it from the container:

```php
use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;

$guest = function (Request $request, Response $response, $next) {
    if ($this->get('auth')) {
        $this->get('flash')->addMessage('warning', 'You need to be logged out to see this page');
        return $response->withRedirect($this->get('router')->pathFor('home'));
    }
    $response = $next($request, $response);
    return $response;
};

```

Questions:

1. Is this a problem for PHP-DI to get objects direct from the container, instead of _Autowiring_?
2. Is there a way to get _Autowiring_ to work with Slim’s Middleware?

* * *

@mnapoli (the author of PHP-DI/Slim-Bridge) just replied to me in Gitter:

only controllers can do dependency injection in parameters for now  
the only feature that PHP-DI brings for middlewares is the ability to do something like this:

```php
$app->get('/auth/register', ['\App\Controllers\Auth\Register', 'getRegister'])->setName('auth.register')->add('GuestMiddleware');

```

i.e. resolve middlewares from the container  
(that way you can do dependency injection in middleware like for a classic service: through the constructor  
but that requires writing middlewares as classes. With closures there is currently no DI in parameters  
FYI this is something that was added very recently in the Silex bridge: [https://github.com/PHP-DI/Silex-Bridge/releases/tag/1.5.0](https://github.com/PHP-DI/Silex-Bridge/releases/tag/1.5.0)  
that would be great to have the same thing for Slim, I’m not working on it at the moment

---

<div class="post-metadata">

### Author: ![JoeBengalen](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@JoeBengalen](https://discourse.slimframework.com/u/JoeBengalen)
#### Post date: [April 6, 2016, 11:18am UTC](https://discourse.slimframework.com/t/middleware-and-di-with-php-di-slim-bridge/91/2 "2016-04-06T11:18:46Z")

</div>

If you want to use autowiring on a function you could use [call](http://php-di.org/doc/container.html#call).

Also instead of creating a second `Flash` instance under a different container key you should use an [alias](http://php-di.org/doc/php-definitions.html#aliases):

```php
$definitions = [
    FlashInterface::class => DI\object(Flash::class),    
    'flash' => DI\get(FlashInterface::class),
];

```