Provides an entity meta relation entity and associated behaviors for relations.

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dev-8.x-1.x 2023-05-24 09:09 UTC


The Entity meta relation module allows to associate extra information stored in independent entities (meta entities) to content (host) entities. This avoids the need to store this information as a content entity field and pollute the content entity keeping metadata information that controls specific entity behaviour outside of its main storage. ​

Content Structure

  • EntityMeta entities are regular content entities that can be fieldable and revisionable.
  • EntityMetaRelation entities hold the relationship between content entities (such as nodes) and their EntityMeta entities. The relations are held directly to content entity revisions and EntityMeta revisions allowing to follow new revisions in both directions. ​ EntityMeta entities require a defined relation between themselves and content (host) entities. Moreover, each EntityMeta bundle is made applicable to each content entity bundle through configuration defined in 3rd party settings. The required configuration can be set automatically by using EntityMetaRelationInstaller service. An example of its usage can be seen in entity_meta_example_install. ​ The entity_meta_example module contain several example plugins that are used for tests but can be used as references.

Support for new content entities

Entity meta relations can be used with any content entity.

However, the emr_node module already provides support for Node entities. It can be used to understand how to provide support for other content entities. ​

  • A new EntityMetaRelation bundle should be created with at least two fields:
    • one EntityReferenceRevision field that targets the (host) content entity revisions (see the emr_node_revision field as an example for relating to Node entities).
    • one field that targets the EntityMeta revisions (see the emr_meta_revision field as an example for relating to the EntityMeta entities. The storage of this field could be reused).
  • The host entity definition should be altered to include the following properties:
    • entity_meta_relation_bundle: Should specify the EntityMetaRelation bundle you created above.
    • entity_meta_relation_content_field: Should specify the field name that relates to the content (host) entity you created above.
    • entity_meta_relation_meta_field: Should specify the field name that relates to the EntityMeta entities you created above.
    • emr_content_form: In case the content (host) entity form should be used to include a form to manipulate the related EntityMeta entities, this should specify the form handler class to use for this. ​

Foe more information, check emr_node_entity_type_alter for an example how this is done for nodes:

The following is defined:

  • The EntityMetaRelation bundle is node_meta_relation, and it has two fields:
    • emr_node_revision: points to the Node entity revision
    • emr_meta_revision: points to the EntityMeta revision
  • The handler class NodeFormHandler is defined to deal with content entity form changes.

EntityMetaRelation plugins

EntityMeta entities are manageable through EntityMetaRelation plugins. The plugin should indicate the EntityMeta bundle it is associated within its definition: ​

E.g from Drupal\entity_meta_speed\Plugin\EntityMetaRelation\SpeedConfiguration:

 *   id = "speed",
 *   label = @Translation("Speed"),
 *   entity_meta_bundle = "speed",
 *   content_form = TRUE,
 *   entity_meta_wrapper_class = "\Drupal\entity_meta_speed\SpeedEntityMetaWrapper",
 *   description = @Translation("Speed.")
 * )

​ This plugin uses the EntityMeta bundle "speed" and provides a wrapper class to manipulate its data through \Drupal\entity_meta_speed\SpeedEntityMetaWrapper. The wrapper is optional. ​

Using Entity Meta Relation API

Content (host) entities can manipulate their EntityMeta entities directly using the Computed field emr_entity_metas. ​

Adding single EntityMeta entity to a content entity

$node_storage = \Drupal::entityTypeManager()->getStorage('node');

// Create a new node.

/** @var \Drupal\node\NodeInterface $node */
$node = $node_storage->create([
  'type' => 'entity_meta_multi_example',
  'title' => 'Node test',

/** @var \Drupal\emr\Field\EntityMetaItemListInterface $entity_meta_list */
$entity_meta_list = $node->get('emr_entity_metas');

// Instantiate a new entity meta of a given bundle. Since it doesn't exist,
// it will be created on the fly.
/** @var \Drupal\emr\Entity\EntityMetaInterface $entity_meta */
$entity_meta = $entity_meta_list->getEntityMeta('visual');

// Set a meta value.
$entity_meta->set('field_color', 'red');

// Attach the new entity meta. This will add it to the list and once the
// node is saved, the relations are created automatically.

​ ​

Adding several EntityMeta entities to content entity

$node_storage = \Drupal::entityTypeManager()->getStorage('node');

// Create a new node.

/** @var \Drupal\node\NodeInterface $node */
$node = $node_storage->create([
  'type' => 'entity_meta_multi_example',
  'title' => 'Node test',

/** @var \Drupal\emr\Field\EntityMetaItemListInterface $entity_meta_list */
$entity_meta_list = $node->get('emr_entity_metas');

$entity_metas = [];
/** @var \Drupal\emr\Entity\EntityMetaInterface $entity_meta */
$entity_meta = $entity_meta_list->getEntityMeta('visual');
$entity_meta->set('field_color', 'red');
$entity_metas[] = $entity_meta;

/** @var \Drupal\emr\Entity\EntityMetaInterface $entity_meta */
$entity_meta = $entity_meta_list->getEntityMeta('audio');
$entity_meta->set('field_volume', 'low');
$entity_metas[] = $entity_meta;

// Set the array of entites meta entities as values.

​ ​

Using an EntityMetaWrapper

EntityMetaWrappers can be defined to interact with an EntityMeta entities without having to interact directly with its fields and configurations. A wrapper is associated with a EntityMetaRelationPlugin through the entity_meta_wrapper_class property ​ So instead of:

$example_meta = $node->get('emr_entity_metas')->getEntityMeta('audio');
$example_meta->set('field_volume', 'medium');

​ The following can be used:

$example_meta = $node->get('emr_entity_metas')->getEntityMeta('audio');

Changing existing EntityMeta

Existing EntityMeta can be altered through the attach() method.

$example_meta = $node->get('emr_entity_metas')->getEntityMeta('audio');

Please note that the attach() method won't do anything if there is no change detected in the EntityMeta entity. ​

Removing existing EntityMeta

Existing EntityMeta entities can be removed from the revision through the detach() method.

$example_meta = $node->get('emr_entity_metas')->getEntityMeta('example_bundle');

Development setup

​ You can build the development site by running the following steps: ​

  • Install the Composer dependencies: ​
composer install

​ A post command hook (drupal:site-setup) is triggered automatically after composer install. It will make sure that the necessary symlinks are properly setup in the development site. It will also perform token substitution in development configuration files such as behat.yml.dist.

This will also:

  • Symlink the theme in ./build/modules/custom/entity_meta_relation so that it's available for the test site
  • Setup Drush and Drupal's settings using values from ./runner.yml.dist.
  • Setup PHPUnit and Behat configuration files using values from ./runner.yml.dist

Please note: project files and directories are symlinked within the test site by using the OpenEuropa Task Runner's Drupal project symlink command.

If you add a new file or directory in the root of the project, you need to re-run drupal:site-setup in order to make sure they are correctly symlinked.

If you don't want to re-run a full site setup for that, you can simply run:

$ ./vendor/bin/run drupal:symlink-project

  • Install test site by running: ​
./vendor/bin/run drupal:site-install

​ The development site web root should be available in the build directory. ​

Using Docker Compose

​ Alternatively, you can build a development site using Docker and Docker Compose with the provided configuration. ​ Docker provides the necessary services and tools such as a web server and a database server to get the site running, regardless of your local host configuration. ​



​ By default, Docker Compose reads two files, a docker-compose.yml and an optional docker-compose.override.yml file. By convention, the docker-compose.yml contains your base configuration and it's provided by default. The override file, as its name implies, can contain configuration overrides for existing services or entirely new services. If a service is defined in both files, Docker Compose merges the configurations. ​ Find more information on Docker Compose extension mechanism on the official Docker Compose documentation. ​


​ To start, run: ​

docker-compose up

​ It's advised to not daemonize docker-compose so you can turn it off (CTRL+C) quickly when you're done working. However, if you'd like to daemonize it, you have to add the flag -d: ​

docker-compose up -d

​ Then: ​

docker-compose exec web composer install
docker-compose exec web ./vendor/bin/run drupal:site-install

​ Using default configuration, the development site files should be available in the build directory and the development site should be available at: ​

Running the tests

​ To run the grumphp checks: ​

docker-compose exec web ./vendor/bin/grumphp run

​ To run the phpunit tests: ​

docker-compose exec web ./vendor/bin/phpunit

​ To run the behat tests: ​

docker-compose exec web ./vendor/bin/behat

Step debugging

To enable step debugging from the command line, pass the XDEBUG_SESSION environment variable with any value to the container:

docker-compose exec -e XDEBUG_SESSION=1 web <your command>

Please note that, starting from XDebug 3, a connection error message will be outputted in the console if the variable is set but your client is not listening for debugging connections. The error message will cause false negatives for PHPUnit tests.

To initiate step debugging from the browser, set the correct cookie using a browser extension or a bookmarklet like the ones generated at ​


​ Please read the full documentation for details on our code of conduct, and the process for submitting pull requests to us. ​


​ We use SemVer for versioning. For the available versions, see the tags on this repository.