How Do I Create Middleware Parameters In Laravel Framework

Middleware provide a convenient mechanism for filtering HTTP requests entering your application. For example, Laravel includes a middleware that verifies the user of your application is authenticated. If the user is not authenticated, the middleware will redirect the user to the login screen. However, if the user is authenticated, the middleware will allow the request to proceed further into the application. Additional middleware can be written to perform a variety of tasks besides authentication. A CORS middleware might be responsible for adding the proper headers to all responses leaving your application. A logging middleware might log all incoming requests to your application. There are several middleware included in the Laravel framework, including middleware for authentication and CSRF protection. All of these middleware are located in the app/Http/Middleware directory.

Middleware can also receive additional parameters. For example, if your application needs to verify that the authenticated user has a given "role" before performing a given action, you could create a CheckRole middleware that receives a role name as an additional argument.

Additional middleware parameters will be passed to the middleware after the $next argument:

<?php

namespace App\Http\Middleware;

use Closure;

class CheckRole
{
    /**
     * Handle the incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @param  string  $role
     * @return mixed
     */
    public function handle($request, Closure $next, $role)
    {
        if (! $request->user()->hasRole($role)) {
            // Redirect...
        }

        return $next($request);
    }

}

Route::put('post/{id}', function ($id) {
    //
})->middleware('role:editor');

Example(1)

php artisan make:middleware RoleMiddleware

2. RoleMiddleware.php in app/Http/Middleware directory and open RoleMiddleware.php file and Implement below code to that file.
In this file checks given parameter userrole is access for current login user or not.

app/Http/Middleware/RoleMiddleware.php

<?php

namespace App\Http\Middleware;

use Closure;
use DB;
use Auth;

class RoleMiddleware
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */

    public function handle($request, Closure $next, $role)
    {
        if (!$request->user()->hasRole($role)) {
            return redirect('/');
        }

        return $next($request);
    }
}

3.Now open kernel.php file and register above middleware in Kernel.php file so open Kernel.php and implement code as below 
app/Http/Kernel.php

namespace App\Http;
use Illuminate\Foundation\Http\Kernel as HttpKernel;
class Kernel extends HttpKernel
{
......
    protected $routeMiddleware = [
        ......
        'role' => \App\Http\Middleware\RoleMiddleware::class,
    ];
}

4.Now cal role middleware in routes.php file.open web.php file and implement code as below 
web.php

Route::get('home', ['as'=>'home','uses'=>'HomeController@index']);


Route::get('demo', ['as'=>'admins','uses'=>'demoController@admins','middleware' => 'role:admin']);