Multilingual

Get current language id

\Drupal::languageManager()->getCurrentLanguage()->getId();

Add t() to classes (services, controllers, etc)

use Drupal\Core\StringTranslation\StringTranslationTrait;

class MyClass {

use StringTranslationTrait;

}

Entity translations

Get translation

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

if ($node->hasTranslation($languageId)) {

$translated = $node->getTranslation($languageId);

}

Add translation

if (!$entity->hasTranslation('fr')) {

$translation = $entity->addTranslation('fr', [

'field_foo' => 'Bonjour'

]);

}