Entities

Load an entity. Can be a config entity also

$node = \Drupal::entityTypeManager()->getStorage('node')->load(23);

$search_api_index = \Drupal::entityTypeManager()->getStorage('search_api')->load('title_records');

Load multiple entities (if no param is passed, all entities are loaded)

$node = \Drupal::entityTypeManager()->getStorage('node')->loadMultiple($entity_ids);

Delete multiple entities

$result = \Drupal::entityQuery('taxonomy_term')

->condition('vid', 'libraries')

->execute();

entity_delete_multiple('taxonomy_term', $result);

Adding a new field to a custom entity

$new_field = BaseFieldDefinition::create('string')

->setLabel(new TranslatableMarkup('New Field'))

->setDescription(new TranslatableMarkup('New field description.'));

\Drupal::entityDefinitionUpdateManager()->installFieldStorageDefinition('<field_name>', '<entity_type_id>', '<provider>', $new_field);

Apply all updates to entities

\Drupal::entityDefinitionUpdateManager()->applyUpdates();

Get bundle field definitions

\Drupal::service('entity_field.manager')->getFieldDefinitions($entity_type, $bundle_id);