Problem in dependency injection in drupal custom module service

Question

I face with a problem in defining service in drupal 8.0 my service is :

services:
  tracking.middleware:
    class: Drupal\mkt_tracking_v2\Middleware\TrackingMiddleware
    arguments: ['@kernel','@config.factory','@request_stack']
    tags:
      - {name: http_middleware, priority: 1000}

the problem is: the object that passes to TrackingMiddleware aren't based on the arguments definition.

as I get this error :

Thu Apr 04 01:51:23.919189 2019] [php7:notice] [pid 28435] [client 127.0.0.1:51962] TypeError: Argument 2 passed to Drupal\mkt_tracking_v2\Middleware\TrackingMiddleware::__construct() must implement interface Drupal\Core\Config\ConfigFactoryInterface, instance of Drupal\Core\DrupalKernel given, called in /home/hossein/Project/Drupal/8.7/web/core/lib/Drupal/Component/DependencyInjection/Container.php on line 274 in /home/hossein/Project/Drupal/8.7/web/modules/Marketing/mkt_tracking_v2/src/Middleware/TrackingMiddleware.php on line 41 #0 /home/hossein/Project/Drupal/8.7/web/core/lib/Drupal/Component/DependencyInjection/Container.php(274): Drupal\mkt_tracking_v2\Middleware\TrackingMiddleware->__construct(Object(Drupal\Core\StackMiddleware\NegotiationMiddleware), Object(Drupal\Core\DrupalKernel), Object(Drupal\Core\Config\ConfigFactory), Object(Symfony\Component\HttpFoundation\RequestStack))\n#1 /home/hossein/Project/Drupal/8.7/web/core/lib/Drupal/Component/DependencyInjection/Container.php(171): Drupal\Component\DependencyInjection\Container->createService(Array, 'tracking.middle...')\n#2 /home/hossein/Project/Drupal/8.7/web/core/lib/Drupal/Component/DependencyInjection/Container.php(480): Drupal\Component\DependencyInjection\Container->get('tracking.middle...', 1)\n#3 /home/hossein/Project/Drupal/8.7/web/core/lib/Drupal/Component/DependencyInjection/Container.php(230): Drupal\Component\DependencyInjection\Container->resolveServicesAndParameters(Array)\n#4 /home/hossein/Project/Drupal/8.7/web/core/lib/Drupal/Component/DependencyInjection/Container.php(171): Drupal\Component\DependencyInjection\Container->createService(Array, 'http_kernel')\n#5 /home/hossein/Project/Drupal/8.7/web/core/lib/Drupal/Core/DrupalKernel.php(1412): Drupal\Component\DependencyInjection\Container->get('http_kernel')\n#6 /home/hossein/Project/Drupal/8.7/web/core/lib/Drupal/Core/DrupalKernel.php(693): Drupal\Core\DrupalKernel->getHttpKernel()\n#7 /home/hossein/Project/Drupal/8.7/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))\n#8 {main}, referer: http://drupal.local/admin/modules/uninstall but as i define the class in this way the constructor parameters is right :

 public function __construct(HttpKernelInterface $app,ConfigFactoryInterface $configFactory,RequestStack $requestStack) {
    $this->app = $app;
    $this->configFactory = $configFactory;
    $this->requestStack = $requestStack;
  }

did I do any mistake in service definition?

Answer 1

From the looks of the core middleware services, the HTTP kernel is automatically provided to the constructor. You don't have to specify it (and even if you did, @kernel is Drupal's kernel, so might not be what you meant).

As an example, ReverseProxyMiddleware's constructor signature:

public function __construct(HttpKernelInterface $http_kernel, Settings $settings) {

And its services entry:

http_middleware.reverse_proxy:
  class: Drupal\Core\StackMiddleware\ReverseProxyMiddleware
  arguments: ['@settings']
  tags:
    - { name: http_middleware, priority: 300 }

Note no explicit @kernel, yet it's the first constructor argument.

So in theory you just need to change you service definition and clear caches:

class: Drupal\mkt_tracking_v2\Middleware\TrackingMiddleware
  arguments: ['@config.factory','@request_stack']
  tags:
    - {name: http_middleware, priority: 1000}