function AjaxColorForm::buildForm
Same name in other branches
- 3.x modules/form_api_example/src/Form/AjaxColorForm.php \Drupal\form_api_example\Form\AjaxColorForm::buildForm()
- 8.x-1.x form_api_example/src/Form/AjaxColorForm.php \Drupal\form_api_example\Form\AjaxColorForm::buildForm()
Overrides FormInterface::buildForm
File
-
modules/
form_api_example/ src/ Form/ AjaxColorForm.php, line 29
Class
- AjaxColorForm
- Implements the ajax demo form controller.
Namespace
Drupal\form_api_example\FormCode
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;
}