Also generate a storage schema class so we can add the 'deleted' field to the proper indexes.

src/TrashStorageTrait.php

@@ -23,4 +23,19 @@ trait TrashStorageTrait {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  protected function getStorageSchema() {
+    if (!isset($this->storageSchema)) {
+      $class = $this->entityType->getHandlerClass('storage_schema') ?: 'Drupal\Core\Entity\Sql\SqlContentEntityStorageSchema';
+
+      // Ensure that we use our generated storage schema class.
+      $class = _trash_generate_storage_class($class, 'storage_schema');
+
+      $this->storageSchema = new $class($this->entityTypeManager, $this->entityType, $this, $this->database, $this->entityFieldManager);
+    }
+    return $this->storageSchema;
+  }
+
 }

templates/TrashStorage.php.twig

@@ -5,7 +5,7 @@ use Drupal\trash\TrashStorageTrait;
 /**
  * Provides a custom storage class for trash-enabled entity types.
  */
-class {{ trash_storage_class }} extends \{{ actual_storage_class }} {
+class {{ trash_class }} extends \{{ original_class }} {
 
   use TrashStorageTrait;
 

templates/TrashStorageSchema.php.twig

+<?php
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+
+/**
+ * Provides a custom storage schema class for trash-enabled entity types.
+ */
+class {{ trash_class }} extends \{{ original_class }} {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $storage_definition, $table_name, array $column_mapping) {
+    $schema = parent::getSharedTableFieldSchema($storage_definition, $table_name, $column_mapping);
+
+    // @todo Add the 'deleted' field to the required indexes.
+
+    return $schema;
+  }
+
+}

trash.module

@@ -37,9 +37,7 @@ function trash_entity_base_field_info(EntityTypeInterface $entity_type) {
         ->setDescription(t('Time when the item got deleted'))
         ->setInternal(TRUE)
         ->setTranslatable(FALSE)
-        ->setRevisionable(TRUE)
-        ->setInitialValue(0)
-        ->setDefaultValue(0);
+        ->setRevisionable(TRUE);
 
     return $base_field_definitions;
   }
@@ -76,23 +74,27 @@ function trash_cache_flush() {
   PhpStorageFactory::get('trash')->deleteAll();
 }
 
-function _trash_generate_storage_class($original_storage_class) {
+function _trash_generate_storage_class($original_class, $type = 'storage') {
+  // Assert that only the supported class types are used.
+  assert($type === 'storage' || $type === 'storage_schema');
+
   $php_storage = PhpStorageFactory::get('trash');
 
-  $trash_class = str_replace('\\', '__', $original_storage_class) . 'Trash';
+  $trash_class = str_replace('\\', '__', $original_class) . 'Trash';
   if (!$php_storage->exists($trash_class . '.php')) {
-    $code = \Drupal::service('twig')->render('@trash/TrashStorage.php.twig', [
-      'trash_storage_class' => $trash_class,
-      'actual_storage_class' => $original_storage_class,
+    $template = ($type === 'storage') ? '@trash/TrashStorage.php.twig' : '@trash/TrashStorageSchema.php.twig';
+    $code = \Drupal::service('twig')->render($template, [
+      'trash_class' => $trash_class,
+      'original_class' => $original_class,
     ]);
 
     $php_storage->save($trash_class . '.php', $code);
   }
 
   if ($php_storage->load($trash_class . '.php')) {
-    // @todo Log a critical error when the storage class could not be loaded?
+    // @todo Log a critical error when the generated class could not be loaded?
     return $trash_class;
   }
 
-  return $original_storage_class;
+  return $original_class;
 }