Laravel 5.4 set locale in session - laravel-5

Question

Update.
I would like to know how to set locale in session.
my language picker isnt' input type, but just text. here is blade fragment - this is language picker:
<div class = "col-lg-5 col-md-5" id = "lang">
<ul id = "lang_menu">
<li class = "language active">Latviešu</a></li>
<li class = "language">Pусский</a></li>
<li class = "language">English</a></li>
</ul>
</div>
Here are routes:
Route::get('/', 'PagesController#index');
Route::get('/mafia', 'PagesController#mafia');
Route::get('/games', 'PagesController#games');
Route::get('/discounts', 'PagesController#discounts');
Route::get('/tournaments', 'PagesController#tournaments');
Route::get('/gallery', 'PagesController#gallery');
Route::get('/aboutus', 'PagesController#aboutus');
also i have transladet files who works fine when i changing locale in config
<<----------UPDATED----------------->>
Now i got so far but still its not working. I made this code from one tutorial where all works. I did the same and its not working.
Here is lang choosing Blade :
<ul id = "lang_menu">
<li class = "language active">Latviešu</li>
<li class = "language">Pусский</li>
<li class = "language">English</li>
</ul>
Here is routes:
Route::get('locale/{locale?}', array('as'=>'set-locale', 'uses'=>'LanguageController#setLocale'));
Here is my LanguageController:
use Illuminate\Http\Request;
use Session;
use URL;
class LanguageController extends Controller
{
public function setLocale($locale='en'){
if (!in_array($locale, ['en', 'ru', 'lv'])){
$locale = 'en';
}
Session::put('locale', $locale);
return redirect(url(URL::previous()));
}
}
And here is middleware "Locale":
use Closure;
use Session;
use Config;
use App;
class Locale
{
/**
* Handle an incoming request.
*
* #param \Illuminate\Http\Request $request
* #param \Closure $next
* #return mixed
*/
public function handle($request, Closure $next)
{
$locale=Session::get('locale', Config::get('app.locale'));
App::setLocale($locale);
return $next($request);
}
}
And added in Kernel.php:
\App\Http\Middleware\Locale::class,
\Illuminate\Session\Middleware\StartSession::class,

Answer 1

You can set a route to configure the locale (see Configuring The Locale), and redirect back to the previous url:
Route::get('locale/{locale}', function ($locale) {
$validLocale = in_array($locale, ['lv', 'ru', 'en']);
if ($validLocale) {
App::setLocale($locale);
}
return back();
});
When visitors select locale, get users to your route:
<div class = "col-lg-5 col-md-5" id = "lang">
<ul id = "lang_menu">
<li class = "language{{ App::isLocale('lv') ? ' active' : '' }}">Latviešu</li>
<li class = "language{{ App::isLocale('ru') ? ' active' : '' }}">Pусский</li>
<li class = "language{{ App::isLocale('en') ? ' active' : '' }}">English</li>
</ul>
</div>

Answer 2

In middleware you must use session obtained from request, not from helper session() or Session::get() !
public function handle($request, Closure $next)
{
if ($request->session()->has('locale') ) {
$locale = $request->session()->get('locale');
App::setLocale($locale);
}
return $next($request);
}