[ * '#type' => 'select', * // … * ], * ]; * $form = [ * // … * 'settings' => $subform, * ]; * @endcode * * All input fields nested under "settings" are then considered part of that * "subform". The concept is used mostly when the subform is defined by a * different class (potentially even in a different module) than the parent * form. This is often the case for plugins: a plugin's buildConfigurationForm() * would then be handed an instance of this interface as the second parameter. * * The benefit of doing this is that the plugin can then just define the form – * and use the form state – as if it would define a "proper" form, not nested in * some other form structure. This means that it won't have to know the key(s) * under which its form structure will be nested – for instance, when retrieving * the form values during form validation or submission. * * Contrary to "proper" forms, subforms don't translate to a

tag in the * HTML response. Instead, they can only be discerned in the HTML code by the * nesting of the input tags' names. * * @see \Drupal\Core\Plugin\PluginFormInterface::buildConfigurationForm() */ interface SubformStateInterface extends FormStateInterface { /** * Gets the complete form state. * * @return \Drupal\Core\Form\FormStateInterface */ public function getCompleteFormState(); }