8. Storing dynamic data in configuration

Apart from content entities there is a second type of entities in Drupal, the configuration entities. These have a machine-readable string ID and can be deployed between different environments along with the rest of the site configuration.

8.1. Create an entity class

While there are some distinctions, creating a configuration entity type is very similar to creating a content entity type.

Create a src/Entity/EventType.php with the following:

<?php

namespace Drupal\event\Entity;

use Drupal\Core\Config\Entity\ConfigEntityBase;

#[ConfigEntityType(
  id: 'event_type',
  label: new TranslatableMarkup('Event type'),
  label_collection: new TranslatableMarkup('Event types'),
  label_singular: new TranslatableMarkup('event type'),
  label_plural: new TranslatableMarkup('event types'),
  config_prefix: 'type',
  entity_keys: [
    'id' => 'id',
    'label' => 'label',
  ],
  config_export: [
    'id',
    'label',
  ],
)]
class EventType extends ConfigEntityBase {

  protected $id;

  protected $label;

}

More information on the above

Configuration prefix:
```
config_prefix: 'type',
```
To clearly identify the source of all configuration, the names of the respective configuration files of configuration entities are automatically prefixed with the module name (event in this case) and a period (.) as a separator. To distinguish different configuration entity types from the same module, each configuration entity type specifies a configuration prefix which is the second part of the configuration file name prefix followed by an additional period. The full name of a configuration entity’s configuration file is, thus, "$module_name.$config_prefix.$entity_id".
Export properties:
```
config_export: [
    'id',
    'label',
],
```
```
protected $id;

protected $label;
```
Configuration entities do not have a notion of (base) field definitions like content entities. Instead simple PHP properties can be declared in the entity class to hold the values of the entity. The names of those properties need to be specified as export properties in the entity annotation.

8.2. Provide a configuration schema

To ensure that the structure of each configuration object is correct, a schema is provided. When importing configuration from another environment, each configuration object is validated against this schema.

Add a config/schema/event.schema.yml with the following:

event.type.*:
  type: config_object
  mapping:
    id:
      type: string
      label: 'ID'
    label:
      type: label
      label: 'Label'

8.3. Install the entity type

Run drush entity:updates

Note that there is no schema change
Create and save an event type

Run the following PHP code:
```
use Drupal\event\Entity\EventType;

EventType::create([
  'id' => 'webinar',
  'label' => 'Webinar',
])->save();
```
Note that there is a new row in the {config} table with the name event.type.webinar

Load the event type by its ID

Run the following PHP code:

use Drupal\event\Entity\EventType;

$event_type = EventType::load('webinar');
$event_type->label();

Note that the proper label is returned.

Update the label of the event type

Run the following PHP code:

use Drupal\event\Entity\EventType;

$event_type = EventType::load('webinar');
$event_type
  ->set('label', 'Online webinar')
  ->save();

Delete the event type

Run the following PHP code:

use Drupal\event\Entity\EventType;

$event_type = EventType::load('webinar')
$event_type->delete();

Note that the row in the {config} table is gone.