getPropertyNames example

/** * The array of options for the widget. */
  protected array $options;

  /** * {@inheritdoc} */
  public function __construct($plugin_id, $plugin_definition, FieldDefinitionInterface $field_definition, array $settings, array $third_party_settings) {
    parent::__construct($plugin_id, $plugin_definition, $field_definition, $settings, $third_party_settings);
    $property_names = $this->fieldDefinition->getFieldStorageDefinition()->getPropertyNames();
    $this->column = $property_names[0];
  }

  /** * {@inheritdoc} */
  public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
    // Prepare some properties for the child methods to build the actual form     // element.     $this->required = $element['#required'];
    $this->multiple = $this->fieldDefinition->getFieldStorageDefinition()->isMultiple();