Delete a custom field from node_field_data table

Question

A custom module added a field to the node_field_data table. Deleting the field in a hook update like this:

function HOOK_update_N() {
  Database::getConnection()->schema()->dropField('node_field_data', 'my_field');
}

deletes the field, but as soon as configuration is imported a Column not found: 1054 Unknown column error is thrown.

[error]  Drupal\Core\Database\DatabaseExceptionWrapper: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'data.my_field' in 'field list': 
SELECT "revision".*, "data"."my_field" AS "my_field"
FROM
"node_field_revision" "revision"
LEFT OUTER JOIN "node_field_data" "data" ON ("revision"."nid" = "data"."nid" AND "revision"."langcode" = "data"."langcode")
WHERE ("revision"."nid" IN (:db_condition_placeholder_0)) AND ("revision"."vid" IN (:db_condition_placeholder_1))
ORDER BY "revision"."nid" ASC; Array
(
    [:db_condition_placeholder_0] => 100000
    [:db_condition_placeholder_1] => 200000
)
 in Drupal\Core\Entity\Sql\SqlContentEntityStorage->loadFromSharedTables() (line 579 of /var/www/html/docroot/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php).

Here’s the same query, only more readable.

SELECT revision.*, data.my_field AS my_field
    FROM node_field_revision revision
    LEFT OUTER JOIN node_field_data data ON (revision.nid = data.nid AND revision.langcode = data.langcode)
    WHERE (revision.nid IN (100000)) AND (revision.vid IN (200000))
    ORDER BY revision.nid;

So the config import is triggering some cleanup and dropField() on the database is not the way to go.

I seem to recall some other modules, maybe lingotek or workbench_moderation, adding a field to the node_field_data table at one point. I wonder how they got their field out of the table if that was so?

The core content_translation module adds field to the node_field_data table.

---

Yes, thanks, the database tables aren't directly accessed. I'm also uninstalling the module, so I'm using hook_uninstall() like this:

/**
 * Implements hook_uninstall().
 */
function my_module_uninstall() {
  $update_manager = \Drupal::entityDefinitionUpdateManager();
  $definition = $update_manager->getFieldStorageDefinition('my_field', 'node');
  $update_manager->uninstallFieldStorageDefinition($definition);
}

But when I run drush -y pmu my_module, I'm getting a

[error] TypeError: Argument 1 passed to Drupal\Core\Entity\EntityDefinitionUpdateManager::uninstallFieldStorageDefinition() must implement interface Drupal\Core\Field\FieldStorageDefinitionInterface, null given,

error.

---

Update: The error was because there was content in the field. We decided to do this in an update hook, not a hook_uninstall hook.

Here's that version of the code:

function my_module_update_N() {
  if (!\Drupal::database()->schema()->fieldExists('node_field_data', 'my_field')) {
    return;
  }

  // First, delete the content from the field.
  \Drupal::database()->query("UPDATE {node_field_data} SET my_field = NULL WHERE my_field IS NOT NULL");

  // Use the update manager to uninstall the field.
  $update_manager = \Drupal::entityDefinitionUpdateManager();
  $definition = $update_manager->getFieldStorageDefinition('my_field', 'node');
  $update_manager->uninstallFieldStorageDefinition($definition);
  $update_manager->updateEntityType($update_manager->getEntityType('node'));

  // Required because other hook updates and/or post-updates may run immediately after.
  drupal_flush_all_caches();
}

I add updateEntityType() and drupal_flush_all_caches() because of the next error. The next error was when the build got to the config:import step, it was throwing this error:

In ExceptionHandler.php line 53:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'my_field' in 'where clause': SELECT 1 AS "expression"
FROM
"node_field_data" "t"
WHERE "my_field" IS NOT NULL
LIMIT 1 OFFSET 0; Array
(
)

In StatementWrapper.php line 145:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'my_field' in 'where clause'

So then we tried the module installer service:

function my_module_update_N() {
  // Use module handler because it removes the my_module field from the node_field_data table.
  if (\Drupal::moduleHandler()->moduleExists('my_module')) {
    \Drupal::service('module_installer')->uninstall(['my_module']);
  }
}

Per the comment in the hook update, not only did the module handler delete the field in node_field_data, but it "alerted" other processes like config:import that the field was gone. The config is imported successfully, the build completes successfully, and the problem has been solved.

Answer 1

Basing on Updating Entities and Fields in Drupal 8, adding and deleting a entity field requires \Drupal::entityDefinitionUpdateManager(). (I changed the second code example to use the same field and entity name used in the first code example.)

A base field is added and removed using code similar to the following one.

$field_storage_definition = BaseFieldDefinition::create('boolean')
  ->setLabel(t('Revision translation affected'))
  ->setDescription(t('Indicates if the last edit of a translation belongs to current revision.'))
  ->setReadOnly(TRUE)
  ->setRevisionable(TRUE)
  ->setTranslatable(TRUE);

\Drupal::entityDefinitionUpdateManager()
  ->installFieldStorageDefinition('revision_translation_affected', 'block_content', 'block_content', $field_storage_definition);

$update_manager = \Drupal::entityDefinitionUpdateManager();
$definition = $update_manager->getFieldStorageDefinition('revision_translation_affected', 'block_content');
$update_manager->uninstallFieldStorageDefinition($definition);

The database tables aren't directly accessed. The update manager takes care of that.