无法将filters.php文件从laravel 4迁移到laravel 5

I just inherited a laravel application and need to migrate it from 4 to 5. Everything is good after following the guide except the filters.php file.

The guide says to move them to the boot method of RouteServiceProvider and replace before filter with middleware but it just won't work. I am new to laravel and not sure how everything works.

This is one of the filters i am trying to migrate:

Route::filter('campaign.edit', function($route)
{
$campaign_id = $route->getParameter('id');
if (is_null(Namespace\Campaign::find($campaign_id))) {
    if (Input::get('campaign_id')) {
        $campaign_id = Input::get('campaign_id');
    } else if (Input::get('track_id')) {
        $track_id = Input::get('track_id');
        $track = Namespace\Track::find($track_id);
        $campaign_id = $track->campaign_id;
    } else {
        return;
    }
}
if (false === Auth::user()->canEditCampaign($campaign_id)) {
    return App::abort(403);
}
});

How can I go about migrating this piece?

Found the solution by taking that function and making a middleware out of it, such as the one below.

namespace App\Http\Middleware;

use Closure;
use NameSpace;
use Input;
use Illuminate\Support\Facades\Auth;

class CampaignEdit
{
public function handle($request, Closure $next)
{
  $campaign_id = $request->route('id');
  if (is_null(NameSpace\Campaign::find($campaign_id))) {
    if (Input::get('campaign_id')) {
      $campaign_id = Input::get('campaign_id');
    } else if (Input::get('track_id')) {
      $track_id = Input::get('track_id');
      $track = NameSpace\Track::find($track_id);
      $campaign_id = $track->campaign_id;
    } else {
      return;
    }
  }
  if (false === Auth::user()->canEditCampaign($campaign_id)) {
    return App::abort(403);
  }


  return $next($request);
  }

}