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- <?php
- namespace Drupal\Core\Render\Element;
- use Drupal\Core\Form\FormStateInterface;
- use Drupal\Core\Render\Element;
- /**
- * Provides a form element for a single checkbox.
- *
- * Properties:
- * - #return_value: The value to return when the checkbox is checked.
- *
- * Usage example:
- * @code
- * $form['copy'] = array(
- * '#type' => 'checkbox',
- * '#title' => $this->t('Send me a copy'),
- * );
- * @endcode
- *
- * @see \Drupal\Core\Render\Element\Checkboxes
- *
- * @FormElement("checkbox")
- */
- class Checkbox extends FormElement {
- /**
- * {@inheritdoc}
- */
- public function getInfo() {
- $class = get_class($this);
- return [
- '#input' => TRUE,
- '#return_value' => 1,
- '#process' => [
- [$class, 'processCheckbox'],
- [$class, 'processAjaxForm'],
- [$class, 'processGroup'],
- ],
- '#pre_render' => [
- [$class, 'preRenderCheckbox'],
- [$class, 'preRenderGroup'],
- ],
- '#theme' => 'input__checkbox',
- '#theme_wrappers' => ['form_element'],
- '#title_display' => 'after',
- ];
- }
- /**
- * {@inheritdoc}
- */
- public static function valueCallback(&$element, $input, FormStateInterface $form_state) {
- if ($input === FALSE) {
- // Use #default_value as the default value of a checkbox, except change
- // NULL to 0, because FormBuilder::handleInputElement() would otherwise
- // replace NULL with empty string, but an empty string is a potentially
- // valid value for a checked checkbox.
- return isset($element['#default_value']) ? $element['#default_value'] : 0;
- }
- else {
- // Checked checkboxes are submitted with a value (possibly '0' or ''):
- // http://www.w3.org/TR/html401/interact/forms.html#successful-controls.
- // For checked checkboxes, browsers submit the string version of
- // #return_value, but we return the original #return_value. For unchecked
- // checkboxes, browsers submit nothing at all, but
- // FormBuilder::handleInputElement() detects this, and calls this
- // function with $input=NULL. Returning NULL from a value callback means
- // to use the default value, which is not what is wanted when an unchecked
- // checkbox is submitted, so we use integer 0 as the value indicating an
- // unchecked checkbox. Therefore, modules must not use integer 0 as a
- // #return_value, as doing so results in the checkbox always being treated
- // as unchecked. The string '0' is allowed for #return_value. The most
- // common use-case for setting #return_value to either 0 or '0' is for the
- // first option within a 0-indexed array of checkboxes, and for this,
- // \Drupal\Core\Render\Element\Checkboxes::processCheckboxes() uses the
- // string rather than the integer.
- return isset($input) ? $element['#return_value'] : 0;
- }
- }
- /**
- * Prepares a #type 'checkbox' render element for input.html.twig.
- *
- * @param array $element
- * An associative array containing the properties of the element.
- * Properties used: #title, #value, #return_value, #description, #required,
- * #attributes, #checked.
- *
- * @return array
- * The $element with prepared variables ready for input.html.twig.
- */
- public static function preRenderCheckbox($element) {
- $element['#attributes']['type'] = 'checkbox';
- Element::setAttributes($element, ['id', 'name', '#return_value' => 'value']);
- // Unchecked checkbox has #value of integer 0.
- if (!empty($element['#checked'])) {
- $element['#attributes']['checked'] = 'checked';
- }
- static::setAttributes($element, ['form-checkbox']);
- return $element;
- }
- /**
- * Sets the #checked property of a checkbox element.
- */
- public static function processCheckbox(&$element, FormStateInterface $form_state, &$complete_form) {
- $value = $element['#value'];
- $return_value = $element['#return_value'];
- // On form submission, the #value of an available and enabled checked
- // checkbox is #return_value, and the #value of an available and enabled
- // unchecked checkbox is integer 0. On not submitted forms, and for
- // checkboxes with #access=FALSE or #disabled=TRUE, the #value is
- // #default_value (integer 0 if #default_value is NULL). Most of the time,
- // a string comparison of #value and #return_value is sufficient for
- // determining the "checked" state, but a value of TRUE always means checked
- // (even if #return_value is 'foo'), and a value of FALSE or integer 0
- // always means unchecked (even if #return_value is '' or '0').
- if ($value === TRUE || $value === FALSE || $value === 0) {
- $element['#checked'] = (bool) $value;
- }
- else {
- // Compare as strings, so that 15 is not considered equal to '15foo', but
- // 1 is considered equal to '1'. This cast does not imply that either
- // #value or #return_value is expected to be a string.
- $element['#checked'] = ((string) $value === (string) $return_value);
- }
- return $element;
- }
- }
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