Issue #2684781 by Sam152: Inject the database service into LinkGeneratorBase

src/LinkGeneratorBase.php

 <?php
+
 /**
  * @file
  * Contains \Drupal\simple_sitemap\LinkGeneratorBase.
@@ -7,7 +8,44 @@
 namespace Drupal\simple_sitemap;
 
 use Drupal\Component\Plugin\PluginBase;
+use Drupal\Core\Database\Connection;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * A link generator plugin base.
+ */
+abstract class LinkGeneratorBase extends PluginBase implements LinkGeneratorInterface, ContainerFactoryPluginInterface {
+
+  /**
+   * The database connection.
+   *
+   * @var \Drupal\Core\Database\Connection
+   */
+  protected $database;
+
+  /**
+   * LinkGeneratorBase constructor.
+   *
+   * @param array $configuration
+   *   The plugin configuration
+   * @param string $plugin_id
+   *   The plugin ID.
+   * @param mixed $plugin_definition
+   *   The plugin definition.
+   * @param \Drupal\Core\Database\Connection $database
+   *   The database connection.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, Connection $database) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->database = $database;
+  }
 
-abstract class LinkGeneratorBase extends PluginBase implements LinkGeneratorInterface {
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static($configuration, $plugin_id, $plugin_definition, $container->get('database'));
+  }
 
 }

src/Plugin/LinkGenerator/Menu.php

@@ -39,7 +39,7 @@ class Menu extends LinkGeneratorBase {
    * {@inheritdoc}
    */
   public function getQuery($bundle) {
-    return \Drupal::database()->select('menu_tree', 'm')
+    return $this->database->select('menu_tree', 'm')
       ->fields('m', array('mlid', 'route_name', 'route_parameters', 'options'))
       ->condition('menu_name', $bundle)
       ->condition('enabled', 1)

src/Plugin/LinkGenerator/NodeType.php

@@ -40,7 +40,7 @@ class NodeType extends LinkGeneratorBase {
    * {@inheritdoc}
    */
   public function getQuery($bundle) {
-    return \Drupal::database()->select('node_field_data', 'n')
+    return $this->database->select('node_field_data', 'n')
       ->fields('n', array('nid', 'changed'))
       ->condition('type', $bundle)
       ->condition('status', 1);

src/Plugin/LinkGenerator/TaxonomyVocabulary.php

@@ -40,7 +40,7 @@ class TaxonomyVocabulary extends LinkGeneratorBase {
    * {@inheritdoc}
    */
   public function getQuery($bundle) {
-    return \Drupal::database()->select('taxonomy_term_field_data', 't')
+    return $this->database->select('taxonomy_term_field_data', 't')
       ->fields('t', array('tid', 'changed'))
       ->condition('vid', $bundle);
   }

src/Plugin/LinkGenerator/User.php

@@ -41,7 +41,7 @@ class User extends LinkGeneratorBase {
    * {@inheritdoc}
    */
   public function getQuery($bundle) {
-    return \Drupal::database()->select('users_field_data', 'u')
+    return $this->database->select('users_field_data', 'u')
       ->fields('u', array('uid', 'changed'))
       ->condition('status', 1);
   }