Providing a custom storage handler

Storage handlers control the loading, saving, and deleting of an entity. Content entity types have the default storage handler of \Drupal\Core\Entity\Sql\SqlContentEntityStorage. Configuration entity types have the default storage handler of \Drupal\Core\Config\Entity\ConfigEntityStorage. These classes can be extended to implement alternative methods and set as the entity type’s storage handler.

In this recipe, we will create a method for the Message entity type created previously in this chapter to load all messages of a specific type.

How to do it…

1. Create a MessageStorage class in the module’s src directory. This class will extend the SqlContentEntityStorage class:

   <?php

   namespace Drupal\mymodule;

   use Drupal\Core\Entity\Sql\SqlContentEntityStorage;

   class MessageStorage extends SqlContentEntityStorage {

   }

The default storage for content entity types is the SqlContentEntityStorage class, which is why we extend...