function Radio::preRenderRadio
Prepares a #type 'radio' render element for input.html.twig.
Parameters
array $element: An associative array containing the properties of the element. Properties used: #required, #return_value, #value, #attributes, #title, #description. The #name property will be sanitized before output. This is currently done by initializing Drupal\Core\Template\Attribute with all the attributes.
Return value
array The $element with prepared variables ready for input.html.twig.
File
- 
              core/
lib/ Drupal/ Core/ Render/ Element/ Radio.php, line 53  
Class
- Radio
 - Provides a form element for a single radio button.
 
Namespace
Drupal\Core\Render\ElementCode
public static function preRenderRadio($element) {
  $element['#attributes']['type'] = 'radio';
  Element::setAttributes($element, [
    'id',
    'name',
    '#return_value' => 'value',
  ]);
  // To avoid auto-casting during '==' we convert $element['#value'] and
  // $element['#return_value'] to strings. It will prevent wrong true-checking
  // for both cases: 0 == 'string' and 'string' == 0, this will occur because
  // all numeric array values will be integers and all submitted values will
  // be strings. Array values are never valid for radios and are skipped. To
  // account for FALSE and empty string values in the #return_value, we will
  // consider any #value that evaluates to empty to be the same as any
  // #return_value that evaluates to empty.
  if (isset($element['#return_value']) && $element['#value'] !== FALSE && !is_array($element['#value']) && (empty($element['#value']) && empty($element['#return_value']) || (string) $element['#value'] === (string) $element['#return_value'])) {
    $element['#attributes']['checked'] = 'checked';
  }
  static::setAttributes($element, [
    'form-radio',
  ]);
  return $element;
}
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