How do I change a field type?

Question

I have a content type with a field_maps whose type is Text (plain, long). I needed to change it to Text (plain).

So I've done this SQL statement:

ALTER TABLE node__field_maps MODIFY field_maps_value VARCHAR(200);

It seems that field_type has changed to VARCHAR(200), but there is still one more problem: On the content type and manage fields tabs, the field is still shown as Text (plain, long).

How do I change it to Text (plain)?

Answer 1

I have also get this kind of issue that change field type from one to another with existing data. So as @Eyal mentioned, we can write an update hook to

1. export data from a field table to a variable
2. remove fields of all bundles
3. add new fields of all bundles
4. restore data to field table

Here is the code example

use \Drupal\field\Entity\FieldStorageConfig;
use \Drupal\field\Entity\FieldConfig;

/**
 * Change node__field_maps from string_long to string type.
 */
function mymodule_update_8XXX() {
  $database = \Drupal::database();
  $table = 'node__field_maps';
  $entity_type = 'node';
  $field_name = 'field_maps';

  $field_storage = FieldStorageConfig::loadByName($entity_type, $field_name);

  if (is_null($field_storage)) {
    return;
  }

  $rows = NULL;

  if ($database->schema()->tableExists($table)) {
    // The table data to restore after the update is completed.
    $rows = $database->select($table, 'n')
      ->fields('n')
      ->execute()
      ->fetchAll();
  }

  $new_fields = array();

  // Use existing field config for new field.
  foreach ($field_storage->getBundles() as $bundle => $label) {
    $field = FieldConfig::loadByName($entity_type, $bundle, $field_name);
    $new_field = $field->toArray();
    $new_field['field_type'] = 'string';
    $new_field['settings'] = array();

    $new_fields[] = $new_field;
  }

  // Deleting field storage which will also delete bundles(fields).
  $new_field_storage = $field_storage->toArray();
  $new_field_storage['type'] = 'string';
  $new_field_storage['settings'] = array(
    'max_length' => 255,
    'is_ascii' => FALSE,
    'case_sensitive' => FALSE,
  );

  $field_storage->delete();

  // Purge field data now to allow new field and field_storage with same name
  // to be created. You may need to increase batch size.
  field_purge_batch(10);

  // Create new field storage.
  $new_field_storage = FieldStorageConfig::create($new_field_storage);
  $new_field_storage->save();

  // Create new fields.
  foreach ($new_fields as $new_field) {
    $new_field = FieldConfig::create($new_field);
    $new_field->save();
  }

  // Restore existing data in the same table.
  if (!is_null($rows)) {
    foreach ($rows as $row) {
      $database->insert($table)
        ->fields((array) $row)
        ->execute();
    }
  }

}

NOTE: Always backup DB and test code before running this code

Other thoughts In my case, we also have exported configures which means the field type and settings are also included in field_storage_config, field_config, entity_form_display, and entity_view_display config files. So we have to update config settings in those files as well. One easy way could be:

• clone your website
• delete the field and add a field with the same name again in field UI
• export configures to use them in the repo
• make sure the config uuid for the field and storage were not changed (change the uuid back if it was) to avoid the import potentially removing data.
• import configure after DB update and clear cache again

This is code is inspired by @drugan in the post https://www.drupal.org/node/2816859

Answer 2

I was facing a similar issue. After running the update_hook described I was still facing a message about "Mismatched entity and/or field definitions" on status overview page. I think it was due to drush entup being removed in Drupal 8.7 I was able to solve this by manually forcing an update of FieldStorageDefinition like this:

function my_module_update_8002() {
  $entity_definition_update_manager = \Drupal::entityDefinitionUpdateManager();
  $entity_type = '[my_entity_type]';
  $field_name = '[my_field_name]';
  $field_storage = FieldStorageConfig::loadByName($entity_type, $field_name);
  $entity_definition_update_manager->updateFieldStorageDefinition($field_storage);
}

Answer 3

Druidfire is your friend. It's pure magic as the name suggests: it's a mini framework to manipulate entity data stored in the default SQL storage and the relevant configuration as well, bypassing most APIs. This particular conversion is not implemented yet but it wouldn't take more than ten minutes to add it, it's really easy. It already does string to formatted text for example with the string2formatted* methods, use these as a template for the change you want to implement.

Answer 4

This is the most optimal solution i found. This snippet works fine in drupal 8.9 and 9.1.

/**
 * Implements hook_update_N().
 */
function CUSTOM_MODULE_update_8001() {

  $entity_type_manager = \Drupal::entityTypeManager();
  $entity_type_manager->clearCachedDefinitions();
  $entity_type = $entity_type_manager->getDefinition('custom_entity');
  \Drupal::entityDefinitionUpdateManager()->installEntityType($entity_type);

  drupal_flush_all_caches();

  return t('Installed the CUSTOM ENTITY entity type');
}