Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/field/src/FieldUninstallValidator.php

@@ -0,0 +1,80 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\field\FieldUninstallValidator.
+ */
+
+namespace Drupal\field;
+
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Extension\ModuleUninstallValidatorInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\Core\StringTranslation\TranslationInterface;
+
+/**
+ * Prevents uninstallation of modules providing active field storage.
+ */
+class FieldUninstallValidator implements ModuleUninstallValidatorInterface {
+
+  use StringTranslationTrait;
+
+  /**
+   * The field storage config storage.
+   *
+   * @var \Drupal\Core\Config\Entity\ConfigEntityStorageInterface
+   */
+  protected $fieldStorageConfigStorage;
+
+  /**
+   * Constructs a new FieldUninstallValidator.
+   *
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
+   *   The entity manager.
+   * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
+   *   The string translation service.
+   */
+  public function __construct(EntityManagerInterface $entity_manager, TranslationInterface $string_translation) {
+    $this->fieldStorageConfigStorage = $entity_manager->getStorage('field_storage_config');
+    $this->stringTranslation = $string_translation;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validate($module) {
+    $reasons = [];
+    if ($field_storages = $this->getFieldStoragesByModule($module)) {
+      // Provide an explanation message (only mention pending deletions if there
+      // remain no actual, non-deleted fields.)
+      $non_deleted = FALSE;
+      foreach ($field_storages as $field_storage) {
+        if (!$field_storage->isDeleted()) {
+          $non_deleted = TRUE;
+          break;
+        }
+      }
+      if ($non_deleted) {
+        $reasons[] = $this->t('Fields type(s) in use');
+      }
+      else {
+        $reasons[] = $this->t('Fields pending deletion');
+      }
+    }
+    return $reasons;
+  }
+
+  /**
+   * Returns all field storages for a specified module.
+   *
+   * @param string $module
+   *   The module to filter field storages by.
+   *
+   * @return \Drupal\field\FieldStorageConfigInterface[]
+   *   An array of field storages for a specified module.
+   */
+  protected function getFieldStoragesByModule($module) {
+    return $this->fieldStorageConfigStorage->loadByProperties(['module' => $module, 'include_deleted' => TRUE]);
+  }
+
+}