class DynamicFormSections in Examples for Developers 8

Same name and namespace in other branches

3.x modules/ajax_example/src/Form/DynamicFormSections.php \Drupal\ajax_example\Form\DynamicFormSections

Dynamically-enabled form with graceful no-JS degradation.

Example of a form with portions dynamically enabled or disabled, but with graceful degradation in the case of no JavaScript.

The idea here is that certain parts of the form don't need to be displayed unless a given option is selected, but then they should be displayed and configured.

The third $no_js_use argument is strictly for demonstrating operation without JavaScript, without making the user/developer turn off JavaScript.

Hierarchy

class \Drupal\Core\Form\FormBase implements ContainerInjectionInterface, FormInterface uses DependencySerializationTrait, LoggerChannelTrait, MessengerTrait, LinkGeneratorTrait, RedirectDestinationTrait, UrlGeneratorTrait, StringTranslationTrait
- class \Drupal\ajax_example\Form\DynamicFormSections

Expanded class hierarchy of DynamicFormSections

1 string reference to 'DynamicFormSections'

ajax_example.routing.yml in ajax_example/ajax_example.routing.yml: ajax_example/ajax_example.routing.yml

File

ajax_example/src/Form/DynamicFormSections.php, line 22

Namespace

Drupal\ajax_example\Form

View source

class DynamicFormSections extends FormBase {

  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'ajax_example_dynamicsectiondegrades';
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state, $nojs = NULL) {

    // Add our CSS and tiny JS to hide things when they should be hidden.
    $form['#attached']['library'][] = 'ajax_example/ajax_example.library';

    // Explanatory text with helpful links.
    $form['info'] = [
      '#markup' => $this
        ->t('<p>Like other examples in this module, this form has a path that
        can be modified with /nojs to simulate its behavior without JavaScript.
        </p><ul>
        <li>@try_it_without_ajax</li>
        <li>@try_it_with_ajax</li>
      </ul>', [
        '@try_it_without_ajax' => Link::createFromRoute($this
          ->t('Try it without AJAX'), 'ajax_example.dynamic_form_sections', [
          'nojs' => 'nojs',
        ])
          ->toString(),
        '@try_it_with_ajax' => Link::createFromRoute($this
          ->t('Try it with AJAX'), 'ajax_example.dynamic_form_sections')
          ->toString(),
      ]),
    ];
    $form['question_type_select'] = [
      // This is our select dropdown.
      '#type' => 'select',
      '#title' => $this
        ->t('Question style'),
      // We have a variety of form items you can use to get input from the user.
      '#options' => [
        'Choose question style' => 'Choose question style',
        'Multiple Choice' => 'Multiple Choice',
        'True/False' => 'True/False',
        'Fill-in-the-blanks' => 'Fill-in-the-blanks',
      ],
      // The #ajax section tells the AJAX system that whenever this dropdown
      // emits an event, it should call the callback and put the resulting
      // content into the wrapper we specify. The questions-fieldset-wrapper is
      // defined below.
      '#ajax' => [
        'wrapper' => 'questions-fieldset-wrapper',
        'callback' => '::promptCallback',
      ],
    ];

    // The CSS for this module hides this next button if JS is enabled.
    $form['question_type_submit'] = [
      '#type' => 'submit',
      '#value' => $this
        ->t('Choose'),
      '#attributes' => [
        'class' => [
          'ajax-example-inline',
        ],
      ],
      // No need to validate when submitting this.
      '#limit_validation_errors' => [],
      '#validate' => [],
    ];

    // This section allows us to demonstrate no-AJAX use without turning off
    // javascript in the browser.
    if ($nojs != 'nojs') {

      // Allow JavaScript to hide the choose button if we're using AJAX.
      $form['question_type_submit']['#attributes']['class'][] = 'ajax-example-hide';
    }
    else {

      // Remove #ajax from the above, so it won't perform AJAX behaviors.
      unset($form['question_type_select']['#ajax']);
    }

    // This fieldset just serves as a container for the part of the form
    // that gets rebuilt. It has a nice line around it so you can see it.
    $form['questions_fieldset'] = [
      '#type' => 'details',
      '#title' => $this
        ->t('Stuff will appear here'),
      '#open' => TRUE,
      // We set the ID of this fieldset to questions-fieldset-wrapper so the
      // AJAX command can replace it.
      '#attributes' => [
        'id' => 'questions-fieldset-wrapper',
      ],
    ];

    // When the AJAX request comes in, or when the user hit 'Submit' if there is
    // no JavaScript, the form state will tell us what the user has selected
    // from the dropdown. We can look at the value of the dropdown to determine
    // which secondary form to display.
    $question_type = $form_state
      ->getValue('question_type_select');
    if (!empty($question_type) && $question_type !== 'Choose question style') {
      $form['questions_fieldset']['question'] = [
        '#markup' => $this
          ->t('Who was the first president of the U.S.?'),
      ];

      // Build up a secondary form, based on the type of question the user
      // chose.
      switch ($question_type) {
        case 'Multiple Choice':
          $form['questions_fieldset']['question'] = [
            '#type' => 'radios',
            '#title' => $this
              ->t('Who was the first president of the United States'),
            '#options' => [
              'George Bush' => 'George Bush',
              'Adam McGuire' => 'Adam McGuire',
              'Abraham Lincoln' => 'Abraham Lincoln',
              'George Washington' => 'George Washington',
            ],
          ];
          break;
        case 'True/False':
          $form['questions_fieldset']['question'] = [
            '#type' => 'radios',
            '#title' => $this
              ->t('Was George Washington the first president of the United States?'),
            '#options' => [
              'George Washington' => 'True',
              0 => 'False',
            ],
            '#description' => $this
              ->t('Click "True" if you think George Washington was the first president of the United States.'),
          ];
          break;
        case 'Fill-in-the-blanks':
          $form['questions_fieldset']['question'] = [
            '#type' => 'textfield',
            '#title' => $this
              ->t('Who was the first president of the United States'),
            '#description' => $this
              ->t('Please type the correct answer to the question.'),
          ];
          break;
      }
      $form['questions_fieldset']['submit'] = [
        '#type' => 'submit',
        '#value' => $this
          ->t('Submit your answer'),
      ];
    }
    return $form;
  }

  /**
   * Final submit handler.
   *
   * Reports what values were finally set.
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $messenger = $this
      ->messenger();

    // This is only executed when a button is pressed, not when the AJAXfield
    // select is changed.
    // Now handle the case of the next, previous, and submit buttons.
    // Only submit will result in actual submission, all others rebuild.
    if ($form_state
      ->getValue('question_type_submit') == 'Choose') {
      $form_state
        ->setValue('question_type_select', $form_state
        ->getUserInput()['question_type_select']);
      $form_state
        ->setRebuild();
    }
    if ($form_state
      ->getValue('submit') == 'Submit your answer') {
      $form_state
        ->setRebuild(FALSE);
      $answer = $form_state
        ->getValue('question');

      // Special handling for the checkbox.
      if ($answer == 1 && $form['questions_fieldset']['question']['#type'] == 'checkbox') {
        $answer = $form['questions_fieldset']['question']['#title'];
      }
      if ($answer == $this
        ->t('George Washington')) {
        $messenger
          ->addMessage($this
          ->t('You got the right answer: @answer', [
          '@answer' => $answer,
        ]));
      }
      else {
        $messenger
          ->addMessage($this
          ->t('Sorry, your answer (@answer) is wrong', [
          '@answer' => $answer,
        ]));
      }
      return;
    }

    // Sets the form to be rebuilt after processing.
    $form_state
      ->setRebuild();
  }

  /**
   * Callback for the select element.
   *
   * Since the questions_fieldset part of the form has already been built during
   * the AJAX request, we can return only that part of the form to the AJAX
   * request, and it will insert that part into questions-fieldset-wrapper.
   *
   * @param array $form
   *   An associative array containing the structure of the form.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @return array
   *   The form structure.
   */
  public function promptCallback(array $form, FormStateInterface $form_state) {
    return $form['questions_fieldset'];
  }

}

Members

Name	Modifiers	Type	Description	Overrides
DependencySerializationTrait::$_entityStorages	protected	property	An array of entity type IDs keyed by the property name of their storages.
DependencySerializationTrait::$_serviceIds	protected	property	An array of service IDs keyed by property name used for serialization.
DependencySerializationTrait::__sleep	public	function		1
DependencySerializationTrait::__wakeup	public	function		2
DynamicFormSections::buildForm	public	function	Form constructor. Overrides FormInterface::buildForm
DynamicFormSections::getFormId	public	function	Returns a unique string identifying the form. Overrides FormInterface::getFormId
DynamicFormSections::promptCallback	public	function	Callback for the select element.
DynamicFormSections::submitForm	public	function	Final submit handler. Overrides FormInterface::submitForm
FormBase::$configFactory	protected	property	The config factory.	1
FormBase::$requestStack	protected	property	The request stack.	1
FormBase::$routeMatch	protected	property	The route match.
FormBase::config	protected	function	Retrieves a configuration object.
FormBase::configFactory	protected	function	Gets the config factory for this form.	1
FormBase::container	private	function	Returns the service container.
FormBase::create	public static	function	Instantiates a new instance of this class. Overrides ContainerInjectionInterface::create	87
FormBase::currentUser	protected	function	Gets the current user.
FormBase::getRequest	protected	function	Gets the request object.
FormBase::getRouteMatch	protected	function	Gets the route match.
FormBase::logger	protected	function	Gets the logger for a specific channel.
FormBase::redirect	protected	function	Returns a redirect response object for the specified route. Overrides UrlGeneratorTrait::redirect
FormBase::resetConfigFactory	public	function	Resets the configuration factory.
FormBase::setConfigFactory	public	function	Sets the config factory for this form.
FormBase::setRequestStack	public	function	Sets the request stack object to use.
FormBase::validateForm	public	function	Form validation handler. Overrides FormInterface::validateForm	62
LinkGeneratorTrait::$linkGenerator	protected	property	The link generator.	1
LinkGeneratorTrait::getLinkGenerator Deprecated	protected	function	Returns the link generator.
LinkGeneratorTrait::l Deprecated	protected	function	Renders a link to a route given a route name and its parameters.
LinkGeneratorTrait::setLinkGenerator Deprecated	public	function	Sets the link generator service.
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.	29
MessengerTrait::messenger	public	function	Gets the messenger.	29
MessengerTrait::setMessenger	public	function	Sets the messenger.
RedirectDestinationTrait::$redirectDestination	protected	property	The redirect destination service.	1
RedirectDestinationTrait::getDestinationArray	protected	function	Prepares a 'destination' URL query parameter for use with \Drupal\Core\Url.
RedirectDestinationTrait::getRedirectDestination	protected	function	Returns the redirect destination service.
RedirectDestinationTrait::setRedirectDestination	public	function	Sets the redirect destination service.
StringTranslationTrait::$stringTranslation	protected	property	The string translation service.	1
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.
UrlGeneratorTrait::$urlGenerator	protected	property	The url generator.
UrlGeneratorTrait::getUrlGenerator Deprecated	protected	function	Returns the URL generator service.
UrlGeneratorTrait::setUrlGenerator Deprecated	public	function	Sets the URL generator service.
UrlGeneratorTrait::url Deprecated	protected	function	Generates a URL or path for a specific route based on the given parameters.

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class DynamicFormSections in Examples for Developers 8

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