title: How to access the $container within middleware class in Slim v3?
body: <p>I've been reading that in Slim v2, $app was bound to the middleware class. I'm finding this not to be the case in v3? Below is my middleware class, but I'm just getting undefined:</p>
  
  <pre><code>&lt;?php
  namespace CrSrc\Middleware;
  
  class Auth
  {
      /**
       * Example middleware invokable class
       *
       * @param  \Psr\Http\Message\ServerRequestInterface $request  PSR7 request
       * @param  \Psr\Http\Message\ResponseInterface      $response PSR7 response
       * @param  callable                                 $next     Next middleware
       *
       * @return \Psr\Http\Message\ResponseInterface
       */
      public function __invoke($request, $response, $next)
      {
          // before
  
  var_dump($this-&gt;getContainer()); // method undefined
  var_dump($this-&gt;auth); exit; // method undefined
          if (! $this-&gt;get('auth')-&gt;isAuthenticated()) {
              // Not authenticated and must be authenticated to access this resource
              return $response-&gt;withStatus(401);
          }
  
          // pass onto the next callable
          $response = $next($request, $response);
  
          // after
  
  
          return $response;
      }
  }
  </code></pre>
  
  <p>What's the correct way to access the DI container within middleware? I'm guessing there ought to be a way?</p>