function BlockPageVariant::build

File

core/modules/block/src/Plugin/DisplayVariant/BlockPageVariant.php, line 125

Class

BlockPageVariant

Provides a page display variant that decorates the main content with blocks.

Namespace

Code

public function build() {
  // Track whether blocks showing the main content and messages are displayed.
  $main_content_block_displayed = FALSE;
  $messages_block_displayed = FALSE;
  $build = [
    '#cache' => [
      'tags' => $this->blockListCacheTags,
    ],
  ];
  // Load all region content assigned via blocks.
  $cacheable_metadata_list = [];
  foreach ($this->blockRepository
    ->getVisibleBlocksPerRegion($cacheable_metadata_list) as $region => $blocks) {
    /** @var \Drupal\block\BlockInterface[] $blocks */
    foreach ($blocks as $key => $block) {
      $block_plugin = $block->getPlugin();
      if ($block_plugin instanceof MainContentBlockPluginInterface) {
        $block_plugin->setMainContent($this->mainContent);
        $main_content_block_displayed = TRUE;
      }
      elseif ($block_plugin instanceof TitleBlockPluginInterface) {
        $block_plugin->setTitle($this->title);
      }
      elseif ($block_plugin instanceof MessagesBlockPluginInterface) {
        $messages_block_displayed = TRUE;
      }
      $build[$region][$key] = $this->blockViewBuilder
        ->view($block);
      // The main content block cannot be cached: it is a placeholder for the
      // render array returned by the controller. It should be rendered as-is,
      // with other placed blocks "decorating" it. Analogous reasoning for the
      // title block.
      if ($block_plugin instanceof MainContentBlockPluginInterface || $block_plugin instanceof TitleBlockPluginInterface) {
        unset($build[$region][$key]['#cache']['keys']);
      }
    }
    if (!empty($build[$region])) {
      // \Drupal\block\BlockRepositoryInterface::getVisibleBlocksPerRegion()
      // returns the blocks in sorted order.
      $build[$region]['#sorted'] = TRUE;
    }
  }
  // If no block that shows the main content is displayed, still show the main
  // content. Otherwise the end user will see all displayed blocks, but not
  // the main content they came for.
  if (!$main_content_block_displayed) {
    $build['content']['system_main'] = $this->mainContent;
  }
  // If no block displays status messages, still render them.
  if (!$messages_block_displayed) {
    $build['content']['messages'] = [
      '#weight' => -1000,
      '#type' => 'status_messages',
      '#include_fallback' => TRUE,
    ];
  }
  // If any render arrays are manually placed, render arrays and blocks must
  // be sorted.
  if (!$main_content_block_displayed || !$messages_block_displayed) {
    unset($build['content']['#sorted']);
  }
  // The access results' cacheability is currently added to the top level of the
  // render array. This is done to prevent issues with empty regions being
  // displayed.
  // This would need to be changed to allow caching of block regions, as each
  // region must then have the relevant cacheable metadata.
  $merged_cacheable_metadata = CacheableMetadata::createFromRenderArray($build);
  foreach ($cacheable_metadata_list as $cacheable_metadata) {
    $merged_cacheable_metadata = $merged_cacheable_metadata->merge($cacheable_metadata);
  }
  $merged_cacheable_metadata->applyTo($build);
  return $build;
}