By longwave on
Change record status: 
Draft (View all draft change records)
Project: 
Drupal core
Introduced in branch: 
11.5.x
Introduced in version: 
11.5.0
Issue links: 
https://www.drupal.org/node/3443882
Description: 

The allow_in_navigation property marks a block as available for placement in the navigation. Setting it previously required an implementation of hook_block_alter().

Blocks can now declare support with the #[AllowInNavigation] attribute. The property is set during block discovery when the navigation module is installed. The module that provides the block does not need to depend on navigation.

Before

#[Hook('block_alter')]
public function blockAlter(&$definitions): void {
  $definitions['my_block']['allow_in_navigation'] = TRUE;
}

After

use Drupal\navigation\Attribute\AllowInNavigation;

#[Block(
  id: 'my_block',
  admin_label: new TranslatableMarkup('My block'),
)]
#[AllowInNavigation]
final class MyBlock extends BlockBase {}

hook_block_alter() can still be used for backward compatibility, including to alter other blocks that you do not own.

Using the attribute on a plugin that is not a block throws InvalidPluginDefinitionException.

Impacts: 
Module developers