Plugin System

When to Use

Read this when creating a custom group relation type plugin to allow a new entity type (or bundle) to be added to groups.

Decision

Situation	Choose	Why
One specific bundle	Single plugin with `entity_bundle: 'article'`	Simple, direct
All bundles of an entity type	Deriver class	Creates one plugin per bundle automatically
Plugin on every group type	`enforced: TRUE`	Auto-installs; use sparingly
Hide from admin UI	`code_only: TRUE`	Install via code/config only

Pattern

use Drupal\group\Plugin\Attribute\GroupRelationType;
use Drupal\group\Plugin\Group\Relation\GroupRelationBase;

#[GroupRelationType(
  id: 'my_module_article',
  entity_type_id: 'node',
  entity_bundle: 'article',        // FALSE to handle all bundles
  label: new TranslatableMarkup('Group article'),
  entity_access: TRUE,             // TRUE = generates CRUD permissions + entity access
  enforced: FALSE,
  pretty_path_key: 'article',
)]
class MyModuleArticle extends GroupRelationBase {
  public function defaultConfiguration() {
    $config = parent::defaultConfiguration();
    $config['entity_cardinality'] = 1; // 0 = unlimited
    return $config;
  }
}

To override a handler (e.g., permissions):

# mymodule.services.yml
group.relation_handler.permission_provider.my_module_article:
  class: 'Drupal\mymodule\Plugin\Group\RelationHandler\ArticlePermissionProvider'
  arguments: ['@group.relation_handler.permission_provider']
  shared: false

Common Mistakes

Wrong: Defining handlers without shared: false → Right: Always add shared: false so each plugin gets its own handler instance.
Wrong: Using the old annotation @GroupContentEnabler → Right: Use the PHP 8 attribute #[GroupRelationType(...)]. The annotation class no longer exists.
Wrong: Not clearing plugin cache when adding new bundles → Right: Call $this->pluginManager->clearCachedDefinitions() in hook_ENTITY_TYPE_insert() for the bundle config entity.
Wrong: Forgetting calculateDependencies() → Right: Add config dependencies for any config entity the plugin depends on (e.g., a node type).

Plugin System

When to Use

Decision

Pattern

Common Mistakes

See Also