function hook_field_widget_multivalue_form_alter

Alter forms for multi-value field widgets provided by other modules.

To alter the individual elements within the widget, loop over \Drupal\Core\Render\Element::children($elements).

Parameters

array $elements: The field widget form elements as constructed by \Drupal\Core\Field\WidgetBase::formMultipleElements().

\Drupal\Core\Form\FormStateInterface $form_state: The current state of the form.

array $context: An associative array containing the following key-value pairs:

• form: The form structure to which widgets are being attached. This may be a full form structure, or a sub-element of a larger form.
• widget: The widget plugin instance.
• items: The field values, as a \Drupal\Core\Field\FieldItemListInterface object.
• default: A boolean indicating whether the form is being shown as a dummy form to set default values.

See also

\Drupal\Core\Field\WidgetBaseInterface::form()

\Drupal\Core\Field\WidgetBase::formMultipleElements()

hook_field_widget_multivalue_WIDGET_TYPE_form_alter()

Related topics

File

core/modules/field/field.api.php, line 259

Field API documentation.

Code

function hook_field_widget_multivalue_form_alter(array &$elements, \Drupal\Core\Form\FormStateInterface $form_state, array $context) {

  // Add a css class to widget form elements for all fields of type mytype.
  $field_definition = $context['items']
    ->getFieldDefinition();
  if ($field_definition
    ->getType() == 'mytype') {

    // Be sure not to overwrite existing attributes.
    $elements['#attributes']['class'][] = 'myclass';
  }
}