Code reference map

19. Code Reference Map

When to Use

Quick reference for finding key classes and files when working with Layout Builder programmatically.

Items

Core Classes

Section Management: - Drupal\layout_builder\Section — Section value object (layout + components) - Drupal\layout_builder\SectionComponent — Component within section (block placement) - Drupal\layout_builder\SectionStorageInterface — Storage interface for sections - Drupal\layout_builder\Plugin\SectionStorage\DefaultsSectionStorage — Default layout storage - Drupal\layout_builder\Plugin\SectionStorage\OverridesSectionStorage — Per-entity override storage

Entity Display: - Drupal\layout_builder\Entity\LayoutBuilderEntityViewDisplay — Extended view display entity - Drupal\layout_builder\Entity\LayoutEntityDisplayInterface — Interface for LB displays

Layout Plugins: - Drupal\Core\Layout\LayoutInterface — Layout plugin interface - Drupal\Core\Layout\LayoutDefault — Base layout plugin class - Drupal\Core\Layout\LayoutDefinition — Layout plugin definition - Drupal\Core\Layout\LayoutPluginManager — Layout plugin discovery

Block Plugins: - Drupal\layout_builder\Plugin\Block\InlineBlock — Non-reusable inline blocks - Drupal\layout_builder\Plugin\Block\FieldBlock — Entity field blocks - Drupal\layout_builder\Plugin\Block\ExtraFieldBlock — Extra field blocks

Events: - Drupal\layout_builder\Event\SectionComponentBuildRenderArrayEvent — Component render event - Drupal\layout_builder\Event\PrepareLayoutEvent — Pre-render layout event - Drupal\layout_builder\LayoutBuilderEvents — Event constant definitions

Services: - inline_block.usage (Drupal\layout_builder\InlineBlockUsage) — Track inline block usage - plugin.manager.layout_builder.section_storage — Section storage plugin manager - plugin.manager.core.layout — Layout plugin manager

Key Files

Configuration Schema: - /core/modules/layout_builder/config/schema/layout_builder.schema.yml — Config structure definitions

Layout Definitions: - /core/modules/layout_builder/layout_builder.layouts.yml — LB-specific layouts - /core/modules/layout_discovery/layout_discovery.layouts.yml — Core general-purpose layouts

Templates: - /core/modules/layout_builder/templates/layout.html.twig — Base layout template - /core/modules/layout_builder/templates/layout-builder-*.html.twig — Admin UI templates - /core/themes/*/templates/layout/*.html.twig — Theme-specific layout templates

Forms: - /core/modules/layout_builder/src/Form/DefaultsEntityForm.php — Edit defaults form - /core/modules/layout_builder/src/Form/OverridesEntityForm.php — Edit overrides form - /core/modules/layout_builder/src/Form/ConfigureSectionForm.php — Section configuration - /core/modules/layout_builder/src/Form/AddBlockForm.php — Add block form

Routing: - /core/modules/layout_builder/layout_builder.routing.yml — LB routes - /core/modules/layout_builder/layout_builder.links.task.yml — Local tasks

Common Patterns

Load section storage:

$storage_manager = \Drupal::service('plugin.manager.layout_builder.section_storage');
$storage = $storage_manager->load('defaults', [
  'display' => EntityViewDisplay::load('node.article.default'),
]);
$sections = $storage->getSections();

Create section:

use Drupal\layout_builder\Section;

$section = new Section('layout_twocol_section', ['label' => '']);
$display->appendSection($section);
$display->save();

Create component:

use Drupal\layout_builder\SectionComponent;

$component = new SectionComponent(
  \Drupal::service('uuid')->generate(),
  'first',
  ['id' => 'system_branding_block', 'label_display' => '0']
);
$section->appendComponent($component);

Get inline block usage:

$usage = \Drupal::service('inline_block.usage');
$orphans = $usage->getUnused(100);

Access entity via context:

// In block plugin build()
$entity = $this->getContextValue('entity');

Common Mistakes

Using wrong namespace → Layout Builder classes in Drupal\layout_builder, core Layout API in Drupal\Core\Layout
Confusing Section and SectionComponent → Section = container with layout. SectionComponent = block in section
Not using services → Access plugin managers and usage tracking via dependency injection, not static calls
Wrong storage plugin → Defaults use DefaultsSectionStorage, overrides use OverridesSectionStorage. Different loading
Forgetting to import classes → Use statements required for Section, SectionComponent, etc.