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class AjaxColorForm in Examples for Developers 3.x

Same name and namespace in other branches
  1. 8 form_api_example/src/Form/AjaxColorForm.php \Drupal\form_api_example\Form\AjaxColorForm

Implements the ajax demo form controller.

This example demonstrates using ajax callbacks to populate the options of a color select element dynamically based on the value selected in another select element in the form.

Hierarchy

Expanded class hierarchy of AjaxColorForm

See also

\Drupal\Core\Form\FormBase

\Drupal\Core\Form\ConfigFormBase

1 string reference to 'AjaxColorForm'
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/AjaxColorForm.php, line 17

Namespace

Drupal\form_api_example\Form
View source 
class AjaxColorForm extends DemoBase {

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

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form['description'] = [
      '#type' => 'item',
      '#markup' => $this
        ->t('This form example demonstrates functioning of an AJAX callback.'),
    ];

    // The #ajax attribute used in the temperature input element defines an ajax
    // callback that will invoke the 'updateColor' method on this form object.
    // Whenever the temperature element changes, it will invoke this callback
    // and replace the contents of the 'color_wrapper' container with the
    // results of this method call.
    $form['temperature'] = [
      '#title' => $this
        ->t('Temperature'),
      '#type' => 'select',
      '#options' => $this
        ->getColorTemperatures(),
      '#empty_option' => $this
        ->t('- Select a color temperature -'),
      '#ajax' => [
        // Could also use [get_class($this), 'updateColor'].
        'callback' => '::updateColor',
        'wrapper' => 'color-wrapper',
      ],
    ];

    // Add a wrapper that can be replaced with new HTML by the ajax callback.
    // This is given the ID that was passed to the ajax callback in the '#ajax'
    // element above.
    $form['color_wrapper'] = [
      '#type' => 'container',
      '#attributes' => [
        'id' => 'color-wrapper',
      ],
    ];

    // Add a color element to the color_wrapper container using the value
    // from temperature to determine which colors to include in the select
    // element.
    $temperature = $form_state
      ->getValue('temperature');
    if (!empty($temperature)) {
      $form['color_wrapper']['color'] = [
        '#type' => 'select',
        '#title' => $this
          ->t('Color'),
        '#options' => $this
          ->getColorsByTemperature($temperature),
      ];
    }

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

  /**
   * Ajax callback for the color dropdown.
   */
  public function updateColor(array $form, FormStateInterface $form_state) {
    return $form['color_wrapper'];
  }

  /**
   * Returns colors that correspond with the given temperature.
   *
   * @param string $temperature
   *   The color temperature for which to return a list of colors. Can be either
   *   'warm' or 'cool'.
   *
   * @return array
   *   An associative array of colors that correspond to the given color
   *   temperature, suitable to use as form options.
   */
  protected function getColorsByTemperature($temperature) {
    return $this
      ->getColors()[$temperature]['colors'];
  }

  /**
   * Returns a list of color temperatures.
   *
   * @return array
   *   An associative array of color temperatures, suitable to use as form
   *   options.
   */
  protected function getColorTemperatures() {
    return array_map(function ($color_data) {
      return $color_data['name'];
    }, $this
      ->getColors());
  }

  /**
   * Returns an array of colors grouped by color temperature.
   *
   * @return array
   *   An associative array of color data, keyed by color temperature.
   */
  protected function getColors() {
    return [
      'warm' => [
        'name' => $this
          ->t('Warm'),
        'colors' => [
          'red' => $this
            ->t('Red'),
          'orange' => $this
            ->t('Orange'),
          'yellow' => $this
            ->t('Yellow'),
        ],
      ],
      'cool' => [
        'name' => $this
          ->t('Cool'),
        'colors' => [
          'blue' => $this
            ->t('Blue'),
          'purple' => $this
            ->t('Purple'),
          'green' => $this
            ->t('Green'),
        ],
      ],
    ];
  }

}

Members

Namesort descending Modifiers Type Description Overrides
AjaxColorForm::buildForm public function Form constructor. Overrides FormInterface::buildForm
AjaxColorForm::getColors protected function Returns an array of colors grouped by color temperature.
AjaxColorForm::getColorsByTemperature protected function Returns colors that correspond with the given temperature.
AjaxColorForm::getColorTemperatures protected function Returns a list of color temperatures.
AjaxColorForm::getFormId public function Returns a unique string identifying the form. Overrides FormInterface::getFormId
AjaxColorForm::updateColor public function Ajax callback for the color dropdown.
DemoBase::submitForm public function Implements a form submit handler. Overrides FormInterface::submitForm 2
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.
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.