Creating a bundle for a content entity type

Bundles allow you to have different variations of a content entity. All bundles share the same base field definitions but not configured fields. This allows each bundle to have its own custom fields. Display modes are also dependent on a specific bundle. This allows each bundle to have its own configuration for the form mode and view mode.

Using the custom entity from the preceding recipe, we will add a configuration entity to act as the bundle. This will allow you to have different message types for multiple custom field configurations.

How to do it…

1. Create a file named MessageType.php in the src/Entity directory so that we can define the MessageType class for our configuration entity type that will provide bundles for our Message entity.
2. The MessageType class will extend the \Drupal\Core\Config\Entity\ConfigEntityBundleBase class and define our entity type’s properties:

   <?php

   namespace Drupal\mymodule\Entity...