class AjaxColorForm
Same name in other branches
- 3.x modules/form_api_example/src/Form/AjaxColorForm.php \Drupal\form_api_example\Form\AjaxColorForm
- 4.0.x modules/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
- class \Drupal\form_api_example\Form\DemoBase extends \Drupal\Core\Form\FormBase
- class \Drupal\form_api_example\Form\AjaxColorForm extends \Drupal\form_api_example\Form\DemoBase
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 form_api_example/
form_api_example.routing.yml - form_api_example/form_api_example.routing.yml
File
-
form_api_example/
src/ Form/ AjaxColorForm.php, line 17
Namespace
Drupal\form_api_example\FormView 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
Title Sort descending | Modifiers | Object type | Summary | Overrides |
---|---|---|---|---|
AjaxColorForm::buildForm | public | function | ||
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 | ||
AjaxColorForm::updateColor | public | function | Ajax callback for the color dropdown. | |
DemoBase::submitForm | public | function | Implements a form submit handler. | 2 |