LanguageMiddleware.php

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Support\Facades\App;
use Illuminate\Support\Facades\Session;

class LangMiddleware
{
    /**
     * lang
     *
     * @var mixed
     */
    private $lang;
    
    /**
     * __construct
     *
     * @return void
     */
    public function __construct()
    {
        $this->lang = Session::get('locale');
    }

    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        if (Session::has('locale')) {
            App::setLocale($this->lang);
        }

        return $next($request);
    }
}