Auth class and auth() function doesnt works in Elo

Im trying get online users from sessions table. To do this, first I added user_id column to sessions table, then I trying update this user_id whenever the page is refreshed. Here is the Online.php model where scopeUpdateCurrent() function check the user and update user_id in sessions table:

namespace App;

use Carbon\Carbon;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Support\Facades\Session;
use Auth;

class Online extends Model
{
  public $table = 'sessions';

  public $timestamps = false;

  public function user()
  {
    return $this->belongsTo('App\User');
  }

  ...

  public function scopeUpdateCurrent(Builder $query)
  {
    $user = auth()->user(); // returns null but user logged in
    // $user = Auth::user(); // returns null too

    return $query->where('id', Session::getId())->update([
        'user_id' => $user ? $user->id : null
    ]);
  }

}

Here is the AppServiceProvider.php where I call that updating:

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use App\Online;

class AppServiceProvider extends ServiceProvider
{
  public function boot()
  {
    Online::updateCurrent();
    ...
  }
  ...
}

The problem is that auth()->user() or Auth::user() returns null in Online.php model but user logged in. For example in some View or in routes.php it returns valid user object.

May not be very clear, because I badly know English. If that write in comments and I will try to describe the issue in detail

This is not a problem with Eloquent models. You are trying to get the authenticated user before sessions have even started.

For example, in app/Http/Kernel.php, you'll see a list of middlewares. One of them is called Illuminate\Session\Middleware\StartSession, which is responsible for starting your session.

Your service provider doesn't have access to these session data because it hasn't started yet. Middlewares kick in later in the lifecycle.

The solution would be to create a middleware to handle this. In your custom middleware, you can add your bit of code, and it will work.

If you're using L5.2 though, the default database session handler already includes user_id and updates it for you.