--- /dev/null
+<?php
+
+namespace Drupal\user\Plugin\views\argument_default;
+
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Cache\CacheableDependencyInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\views\Plugin\views\argument_default\ArgumentDefaultPluginBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\user\UserInterface;
+use Drupal\node\NodeInterface;
+
+/**
+ * Default argument plugin to extract a user from request.
+ *
+ * @ViewsArgumentDefault(
+ * id = "user",
+ * title = @Translation("User ID from route context")
+ * )
+ */
+class User extends ArgumentDefaultPluginBase implements CacheableDependencyInterface {
+
+ /**
+ * The route match.
+ *
+ * @var \Drupal\Core\Routing\RouteMatchInterface
+ */
+ protected $routeMatch;
+
+ /**
+ * Constructs a new User instance.
+ *
+ * @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\Routing\RouteMatchInterface $route_match
+ * The route match.
+ */
+ public function __construct(array $configuration, $plugin_id, $plugin_definition, RouteMatchInterface $route_match) {
+ parent::__construct($configuration, $plugin_id, $plugin_definition);
+
+ $this->routeMatch = $route_match;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+ return new static(
+ $configuration,
+ $plugin_id,
+ $plugin_definition,
+ $container->get('current_route_match')
+ );
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function defineOptions() {
+ $options = parent::defineOptions();
+ $options['user'] = ['default' => ''];
+
+ return $options;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function buildOptionsForm(&$form, FormStateInterface $form_state) {
+ $form['user'] = [
+ '#type' => 'checkbox',
+ '#title' => $this->t('Also look for a node and use the node author'),
+ '#default_value' => $this->options['user'],
+ ];
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getArgument() {
+
+ // If there is a user object in the current route.
+ if ($user = $this->routeMatch->getParameter('user')) {
+ if ($user instanceof UserInterface) {
+ return $user->id();
+ }
+ }
+
+ // If option to use node author; and node in current route.
+ if (!empty($this->options['user']) && $node = $this->routeMatch->getParameter('node')) {
+ if ($node instanceof NodeInterface) {
+ return $node->getOwnerId();
+ }
+ }
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getCacheMaxAge() {
+ return Cache::PERMANENT;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getCacheContexts() {
+ return ['url'];
+ }
+
+}