How to properly delete fields, programmatically?

Question

I have two content types on my site and I just deleted all the nodes using $node->delete().

For one of the content types, I noticed that the node body fields did not get deleted, nor did one of the custom fields I made for the content type. All the fields for my other content type were deleted .

So I researched and found the field_purge_field() function. I am not sure how to actually use the function, which is defined as function field_purge_field(FieldConfigInterface $field).
Can someone describe how I would actually load a field and then delete it in this manner (or in a better manner)?

Could I just truncate the tables?

Answer 1

field_purge_field() is described as follows:

This function assumes all data for the field has already been purged and should only be called by field_purge_batch().

On Drupal, fields are effectively removed during cron tasks; in fact, field_purge_batch() is called from field_cron(), the implementation of hook_cron() done from the Field module. There is no need for you to call neither field_purge_field() nor field_purge_batch().

If you want to write code to purge fields for a node bundle, that code would be similar to the following one. (See the notes after the code, thought.)

  $properties = array(
    'entity_type' => 'node',
    'bundle' => 'Your bundle (a.k.a. content type)',
    'include_deleted' => TRUE,
  );

  $entity_manager = \Drupal::entityTypeManager();

  $fields = $entity_manager->getStorage('field_config')->loadByProperties($properties);

  $info = $entity_manager->getDefinitions();
  foreach ($fields as $field) {
    $entity_type = $field->getTargetEntityTypeId();

    // Proceed only if the module implementing the entity has not been uninstalled already.
    if (isset($info[$entity_type])) {
      $entity_manager->getStorage($entity_type)->purgeFieldData($field, 100);
      field_purge_field($field);
    }
  }

Notes

• Purging the fields is thought to be ran during cron tasks; that is why Drupal::entityManager()->getStorage()->purgeFieldData() requires the batch size as argument. I used a value of 100, which would possibly allow the code to purge all the fields for that content type, but it could also cause a PHP timeout error. It would be better to run the code from PHP CLI, in order to avoid any execution time out.
• You should not need to use this code; in most of the cases, you should execute the cron tasks (which is when Drupal purges the fields of a deleted bundle), or use Drush to purge the fields, either running hook_cron() with it, or executing a specific Drush command (if it exists).

As for truncating the tables, that is the wrong way to proceed. It would not allow Drupal and third-party modules to delete the data they have for the fields; even if you know which tables Drupal uses, you could forget a table used by third-party modules.

Answer 2

The updated version for Drupal 8.3.x using non deprecated functions:

/**
 * Removes field_MY_FIELD_NAME.
 */
function MYMODULE_update_8001() {
  /* @var $entityFieldManager Drupal\Core\Entity\EntityFieldManager */
  $entityFieldManager = Drupal::service('entity_field.manager');

  $fields = $entityFieldManager->getFieldDefinitions('ENTITY_TYPE', 'BUNDLE');

  if (isset($fields['field_MY_FIELD_NAME'])) {
    $fields['field_MY_FIELD_NAME']->delete();
  }
}

Replace the following:

1. ENTITY_TYPE by the entity type, e.g.: 'taxonomy_term', 'node'...
2. BUNDLE by the bundle, e.g.: 'article', 'tags'...
3. field_MY_FIELD_NAME by the field machine name, e.g.: 'field_description'...

Answer 3

The following will delete content and config of a field in all places used on the same entity type. NOTE: in D7 fields could be used across entity types (i.e. same field used on different bundles of same entity type) but in D8, this is not allowed:

use Drupal\field\Entity\FieldStorageConfig;
FieldStorageConfig::loadByName(ENTITY_TYPE_NAME, FIELD_NAME)->delete();

As with the other methods above, this will result in field remnants being left behind in the key_value and cachetags tables. CRON runs will remove remnants from the key_value table but I have not yet found a way to remove remnants from the cachetags table (short of simply using direct db calls).

[EDIT] I stated that field remnants from key_value table would be removed during CRON; but in fact this only occurs if there had been data in that field. Not sure why this is different but likely a core bug.

Answer 4

I found this code for drupal 8 that worked very good for me here https://gist.github.com/jacerider/78b926acbb201666a0fc3a1f8102cb44

This empty the field, them remove field from bundle

I just added in a hook_update_N() https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21Extension%21module.api.php/function/hook_update_N/8.2.x

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

$bundles = ['user'];

$fields['user_picture'] = [
  'entity_type' => 'user',
];

foreach ($bundles as $bundle) {
  foreach ($fields as $field_name => $config) {
    $field = FieldConfig::loadByName($config['entity_type'], $bundle, $field_name);
    if (!empty($field)) {
      $field->delete();
    }
  }
}

foreach ($fields as $field_name => $config) {
  $field_storage = FieldStorageConfig::loadByName($config['entity_type'], $field_name);
  if (!empty($field_storage)) {
    $field_storage->delete();
  }
}

Answer 5

On Drupal 8 we had a lot of issues after uninstalling the domain module.

We solved this with an install file

@file my_module.install

/**
 * Implements hook_update_N().
 */
function my_module_update_8800(&$sandbox) {
  /** @var \Drupal\Core\Field\DeletedFieldsRepositoryInterface $deleted_fields_repository */
  $deleted_fields_repository = \Drupal::service('entity_field.deleted_fields_repository');
  $fields = $deleted_fields_repository->getFieldDefinitions();
  foreach ($fields as $field) {
    field_purge_field($field);
  }
}

Hope this helps someone.