How do I get the currently logged-in user? I have a site running on Drupal 8 with a login module. I want to get the user ID for the currently logged-in user to later execute a database query.
This is the code I am using.
$user = \Drupal\user\Entity\User::load(\Drupal::currentUser()-&gt;id());
$uid = $user-&gt;get('uid')-&gt;value;
echo $uid;

In the controller of a custom module, this code works only between all using and the class controller uses the following code.
namespace Drupal\CoopMatha_adh_apport\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\Node\Entity\Node;
use Drupal\CoopMatha_adh_apport\Repository;
use Drupal\matha_tools\Controller\ListeController;
use Drupal\matha_tools\Controller;

$userCurrent = \Drupal::currentUser();
$user = \Drupal\user\Entity\User::load($userCurrent-&gt;id());
$uid= $user-&gt;get('uid')-&gt;value;
echo $uid;  

class RapportsController extends ControllerBase {    

  // I want the user ID here.
  public function filtrer($firstLetter='', $nbr_ligne='') {
    // …
  }

}

How do I get the currently logged-in user ID in the controller class?
How do I get the currently logged-in user ID in the controller class?

Controllers have a currentUser method:
public function filtrer($firstLetter='', $nbr_ligne='') {
  $current_user_id = $this-&gt;currentUser()-&gt;id();
}