--- /dev/null
+<?php
+
+namespace Drupal\block_content;
+
+use Drupal\Core\Entity\Display\EntityViewDisplayInterface;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\EntityViewBuilder;
+
+/**
+ * View builder handler for custom blocks.
+ */
+class BlockContentViewBuilder extends EntityViewBuilder {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function view(EntityInterface $entity, $view_mode = 'full', $langcode = NULL) {
+ return $this->viewMultiple([$entity], $view_mode, $langcode)[0];
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function viewMultiple(array $entities = [], $view_mode = 'full', $langcode = NULL) {
+ $build_list = parent::viewMultiple($entities, $view_mode, $langcode);
+ // Apply the buildMultiple() #pre_render callback immediately, to make
+ // bubbling of attributes and contextual links to the actual block work.
+ // @see \Drupal\block\BlockViewBuilder::buildBlock()
+ unset($build_list['#pre_render'][0]);
+ return $this->buildMultiple($build_list);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function getBuildDefaults(EntityInterface $entity, $view_mode) {
+ $build = parent::getBuildDefaults($entity, $view_mode);
+ // The custom block will be rendered in the wrapped block template already
+ // and thus has no entity template itself.
+ unset($build['#theme']);
+ return $build;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ protected function alterBuild(array &$build, EntityInterface $entity, EntityViewDisplayInterface $display, $view_mode) {
+ parent::alterBuild($build, $entity, $display, $view_mode);
+ // Add contextual links for this custom block.
+ if (!$entity->isNew()) {
+ $build['#contextual_links']['block_content'] = [
+ 'route_parameters' => ['block_content' => $entity->id()],
+ 'metadata' => ['changed' => $entity->getChangedTime()],
+ ];
+ }
+ }
+
+}