public function Simplest::buildForm in Examples for Developers 3.x
Same name and namespace in other branches
- 8 ajax_example/src/Form/Simplest.php \Drupal\ajax_example\Form\Simplest::buildForm()
Form constructor.
Parameters
array $form: An associative array containing the structure of the form.
\Drupal\Core\Form\FormStateInterface $form_state: The current state of the form.
Return value
array The form structure.
Overrides FormInterface::buildForm
File
- modules/
ajax_example/ src/ Form/ Simplest.php, line 23
Class
- Simplest
- A relatively simple AJAX demonstration form.
Namespace
Drupal\ajax_example\FormCode
public function buildForm(array $form, FormStateInterface $form_state) {
$form['changethis'] = [
'#title' => $this
->t("Choose something and explain why"),
'#type' => 'select',
'#options' => [
'one' => 'one',
'two' => 'two',
'three' => 'three',
],
'#ajax' => [
// #ajax has two required keys: callback and wrapper.
// 'callback' is a function that will be called when this element
// changes.
'callback' => '::promptCallback',
// 'wrapper' is the HTML id of the page element that will be replaced.
'wrapper' => 'replace-textfield-container',
],
];
// The 'replace-textfield-container' container will be replaced whenever
// 'changethis' is updated.
$form['replace_textfield_container'] = [
'#type' => 'container',
'#attributes' => [
'id' => 'replace-textfield-container',
],
];
$form['replace_textfield_container']['replace_textfield'] = [
'#type' => 'textfield',
'#title' => $this
->t("Why"),
];
// An AJAX request calls the form builder function for every change.
// We can change how we build the form based on $form_state.
$value = $form_state
->getValue('changethis');
// The getValue() method returns NULL by default if the form element does
// not exist. It won't exist yet if we're building it for the first time.
if ($value !== NULL) {
$form['replace_textfield_container']['replace_textfield']['#description'] = $this
->t("Say why you chose '@value'", [
'@value' => $value,
]);
}
return $form;
}