public static BlockViewBuilder::preRender($build)
#pre_render callback for building a block.
Renders the content using the provided block plugin, and then:
- if there is no content, aborts rendering, and makes sure the block won't be rendered.
- if there is content, moves the contextual links from the block content to the block itself.
File
- core/modules/block/src/BlockViewBuilder.php, line 202
Class
- BlockViewBuilder
- Provides a Block view builder.
Namespace
Drupal\block
Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | public static function preRender($build) { $content = $build['#block']->getPlugin()->build(); // Remove the block entity from the render array, to ensure that blocks // can be rendered without the block config entity. unset($build['#block']); if ($content !== NULL && !Element::isEmpty($content)) { // Place the $content returned by the block plugin into a 'content' child // element, as a way to allow the plugin to have complete control of its // properties and rendering (for instance, its own #theme) without // conflicting with the properties used above, or alternate ones used by // alternate block rendering approaches in contrib (for instance, Panels). // However, the use of a child element is an implementation detail of this // particular block rendering approach. Semantically, the content returned // by the plugin "is the" block, and in particular, #attributes and // #contextual_links is information about the *entire* block. Therefore, // we must move these properties from $content and merge them into the // top-level element. foreach (array('#attributes', '#contextual_links') as $property) { if (isset($content[$property])) { $build[$property] += $content[$property]; unset($content[$property]); } } $build['content'] = $content; } // Either the block's content is completely empty, or it consists only of // cacheability metadata. else { // Abort rendering: render as the empty string and ensure this block is // render cached, so we can avoid the work of having to repeatedly // determine whether the block is empty. For instance, modifying or adding // entities could cause the block to no longer be empty. $build = array( '#markup' => '', '#cache' => $build['#cache'], ); // If $content is not empty, then it contains cacheability metadata, and // we must merge it with the existing cacheability metadata. This allows // blocks to be empty, yet still bubble cacheability metadata, to indicate // why they are empty. if (!empty($content)) { CacheableMetadata::createFromRenderArray($build) ->merge(CacheableMetadata::createFromRenderArray($content)) ->applyTo($build); } } return $build;} |
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