function BlockPageVariant::build

Overrides VariantInterface::build

File

core/modules/block/src/Plugin/DisplayVariant/BlockPageVariant.php, line 126

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;
}