Uid.php

<?php

namespace Drupal\user\Plugin\views\argument;

use Drupal\Core\Entity\EntityStorageInterface;
use Drupal\views\Plugin\views\argument\NumericArgument;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Argument handler to accept a user id.
 *
 * @ingroup views_argument_handlers
 *
 * @ViewsArgument("user_uid")
 */
class Uid extends NumericArgument {
    
    /**
     * The user storage.
     *
     * @var \Drupal\Core\Entity\EntityStorageInterface
     */
    protected $storage;
    
    /**
     * Constructs a \Drupal\user\Plugin\views\argument\Uid object.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin_id for the plugin instance.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\Core\Entity\EntityStorageInterface $storage
     *   The user storage.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityStorageInterface $storage) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->storage = $storage;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('entity_type.manager')
            ->getStorage('user'));
    }
    
    /**
     * Override the behavior of title(). Get the name of the user.
     *
     * @return array
     *   A list of usernames.
     */
    public function titleQuery() {
        return array_map(function ($account) {
            return $account->label();
        }, $this->storage
            ->loadMultiple($this->value));
    }

}