class StateDemo in Examples for Developers 3.x

Implements the state demo form controller.

This example demonstrates using the #states property to bind the visibility of a form element to the value of another element in the form. In the example, when the user checks the "Need Special Accommodation" checkbox, additional form elements are made visible.

The submit handler for this form is implemented by the \Drupal\form_api_example\Form\DemoBase class.

Hierarchy

• class \Drupal\Core\Form\FormBase implements ContainerInjectionInterface, FormInterface uses DependencySerializationTrait, LoggerChannelTrait, MessengerTrait, RedirectDestinationTrait, StringTranslationTrait
  • class \Drupal\form_api_example\Form\DemoBase
    • class \Drupal\form_api_example\Form\StateDemo

See also

\Drupal\Core\Form\FormBase

\Drupal\form_api_example\Form\DemoBase

drupal_process_states()

1 string reference to 'StateDemo'

form_api_example.routing.yml in modules/form_api_example/form_api_example.routing.yml

modules/form_api_example/form_api_example.routing.yml

File

modules/form_api_example/src/Form/StateDemo.php, line 22

Namespace

Drupal\form_api_example\Form

class StateDemo extends DemoBase {

  /**
   * Build the simple form.
   *
   * @inheritdoc
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form['description'] = [
      '#type' => 'item',
      '#markup' => $this
        ->t('This example demonstrates the #states property. #states makes an element visibility dependent on another.'),
    ];
    $form['needs_accommodation'] = [
      '#type' => 'checkbox',
      '#title' => 'Need Special Accommodations?',
    ];

    // The #states property used here binds the visibility of the
    // container element to the value of the needs_accommodation checkbox above.
    $form['accommodation'] = [
      '#type' => 'container',
      '#attributes' => [
        'class' => 'accommodation',
      ],
      // #states is an associative array. Each key is the name of a state to
      // apply to the element, such as 'visible'. Each value is another array,
      // making a list of conditions that denote when the state should be
      // applied. Every condition is a key/value pair, whose key is a jQuery
      // selector that denotes another element on the page, and whose value is
      // an array of conditions, which must be met on in order for the state to
      // be applied.
      //
      // For additional documentation on the #states property including a list
      // of valid states and conditions see drupal_process_states().
      '#states' => [
        // The state being affected is "invisible".
        'invisible' => [
          // Drupal will only apply this state when the element that satisfies
          // the selector input[name="needs_accommodation"] is un-checked.
          ':input[name="needs_accommodation"]' => [
            'checked' => FALSE,
          ],
        ],
      ],
    ];
    $form['accommodation']['diet'] = [
      '#type' => 'textfield',
      '#title' => $this
        ->t('Dietary Restrictions'),
    ];

    // Add a submit button that handles the submission of the form.
    $form['actions']['submit'] = [
      '#type' => 'submit',
      '#value' => $this
        ->t('Submit'),
    ];
    return $form;
  }

  /**
   * Getter method for Form ID.
   *
   * @inheritdoc
   */
  public function getFormId() {
    return 'form_api_example_state_demo';
  }

  /**
   * Implements submitForm callback.
   *
   * @inheritdoc
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {

    // Find out what was submitted.
    $values = $form_state
      ->getValues();
    if ($values['needs_accommodation']) {
      $this
        ->messenger()
        ->addMessage($this
        ->t('Dietary Restriction Requested: %diet', [
        '%diet' => $values['diet'],
      ]));
    }
  }

}

Members

Name	Modifiers	Type	Description	Overrides
DependencySerializationTrait::$_entityStorages	protected	property
DependencySerializationTrait::$_serviceIds	protected	property
DependencySerializationTrait::__sleep	public	function		2
DependencySerializationTrait::__wakeup	public	function		2
FormBase::$configFactory	protected	property	The config factory.	3
FormBase::$requestStack	protected	property	The request stack.	1
FormBase::$routeMatch	protected	property	The route match.
FormBase::config	protected	function	Retrieves a configuration object.
FormBase::configFactory	protected	function	Gets the config factory for this form.	3
FormBase::container	private	function	Returns the service container.
FormBase::create	public static	function	Instantiates a new instance of this class. Overrides ContainerInjectionInterface::create	105
FormBase::currentUser	protected	function	Gets the current user.
FormBase::getRequest	protected	function	Gets the request object.
FormBase::getRouteMatch	protected	function	Gets the route match.
FormBase::logger	protected	function	Gets the logger for a specific channel.
FormBase::redirect	protected	function	Returns a redirect response object for the specified route.
FormBase::resetConfigFactory	public	function	Resets the configuration factory.
FormBase::setConfigFactory	public	function	Sets the config factory for this form.
FormBase::setRequestStack	public	function	Sets the request stack object to use.
FormBase::validateForm	public	function	Form validation handler. Overrides FormInterface::validateForm	72
LoggerChannelTrait::$loggerFactory	protected	property	The logger channel factory service.
LoggerChannelTrait::getLogger	protected	function	Gets the logger for a specific channel.
LoggerChannelTrait::setLoggerFactory	public	function	Injects the logger channel factory.
MessengerTrait::$messenger	protected	property	The messenger.	27
MessengerTrait::messenger	public	function	Gets the messenger.	27
MessengerTrait::setMessenger	public	function	Sets the messenger.
RedirectDestinationTrait::$redirectDestination	protected	property	The redirect destination service.	1
RedirectDestinationTrait::getDestinationArray	protected	function	Prepares a 'destination' URL query parameter for use with \Drupal\Core\Url.
RedirectDestinationTrait::getRedirectDestination	protected	function	Returns the redirect destination service.
RedirectDestinationTrait::setRedirectDestination	public	function	Sets the redirect destination service.
StateDemo::buildForm	public	function	Build the simple form. Overrides FormInterface::buildForm
StateDemo::getFormId	public	function	Getter method for Form ID. Overrides FormInterface::getFormId
StateDemo::submitForm	public	function	Implements submitForm callback. Overrides DemoBase::submitForm
StringTranslationTrait::$stringTranslation	protected	property	The string translation service.	4
StringTranslationTrait::formatPlural	protected	function	Formats a string containing a count of items.
StringTranslationTrait::getNumberOfPlurals	protected	function	Returns the number of plurals supported by a given language.
StringTranslationTrait::getStringTranslation	protected	function	Gets the string translation service.
StringTranslationTrait::setStringTranslation	public	function	Sets the string translation service to use.	2
StringTranslationTrait::t	protected	function	Translates a string to the current language or to a given language.