How to set #default_value for radio button on Ajax Callback?

Question

I've a form having a radios and 'select list with Ajax callback event'. When user changed selection from the select box, I tried to set the default_value for radio button. but it doesn't work.

In the function check() I'm able to get the changed $id value every time I change the select list, but the default_value not working. it's always checked to the value 1 ('Yes').

I've tried like following but not working.

/**
 * Form.
 */
function myform($form, &$form_state) {
    $current_items = array(1=> 'Yes',2 => 'No');
    $form['current_items'] = array(
      '#title' => t('Change value'),
      '#type' => 'select',
      '#options' => $current_items,
      '#ajax' => array(
        'callback' => 'ajax_change_callback',
        'wrapper' => 'change-div',
      ),
    );
    $form['change_fieldset'] = array(
      '#prefix' => '<div id="change-div">',
      '#suffix' => '</div>',
      '#type' => 'fieldset',
    );

    if (!empty($form_state['values']['current_items'])) {
      $form['change_fieldset']['checkin_form'] = check($form_state['values']['current_items']);
    }
    else {
      $form['change_fieldset']['checkin_form'] = check(1);
    }

  return $form;
}

/**
 * Form callback.
 */
function ajax_change_callback($form, $form_state) {
  return $form['change_fieldset'];
}

/**
 * Callback Form.
 */
function check($id) {
    $items = array(1 => 'Yes', 2 => 'No');
    $form['checkin'] = array(
      '#title' => $id,
      '#type' => 'radios',
      '#options' => $items,
      '#default_value' => $id,
    );
    return $form;
}

Answer 1

Please check if this works

$commands[] = ajax_command_invoke('#my-radio-button-id', 'val', array(array('checked' => TRUE)));

Ref: http://handsomedogstudio.com/setting-radio-button-values-drupal-ajax-call

Answer 2

This was so frustrating to make work. Hope this helps someone. related Ajax callback change "checked" radio button Can't update radio button fields after ajax callback

use Drupal\Core\Ajax\AjaxResponse;
use Drupal\Core\Ajax\InvokeCommand;
... in the buildForm
$form['container']['steps'] = [
  '#type' => 'radios',
  '#title' => $this->t('Steps'),
  '#default_value' => '0',
  '#options' => $form_state->get('multiform_steps'),
  '#required' => TRUE,
];
...
$form['actions']['gotonext_'.$key] = [
   '#type' => 'button',
   '#value' => $this->t('Next'),
      '#data' => $nextStepKey,
      '#states' => [
        'visible' => [
          ':input[name="steps"]' => ['value' => $key],
        ],
      ],
      '#ajax' => [
        'callback' => '::nextStepCallback',
      ],
    ];
...
public function nextStepCallback(array &$form, FormStateInterface $form_state) {
$next_step = (string) $form_state->getTriggeringElement()['#data'];


$response = new AjaxResponse();
//the jquery command to run jQuery('#steps-wrapper .fieldset-wrapper input[name=steps][value=3]').attr('checked', true)
$selector='#steps-wrapper .fieldset-wrapper input[name=steps][value='.$next_step.']'; // A jQuery selector
$method='click'; // The name of a jQuery method to invoke. 
$arguments=[];//['class1','class2']; // (Optional) An array of arguments to pass to the method. 
$response->addCommand(new InvokeCommand($selector,$method,$arguments));
return $response;
}

Answer 3

For Drupal 8+:

$inputs = $form_state->getUserInput(); 
unset($inputs[$item]); 
$form_state->setUserInput($inputs); 

For Drupal 7:

unset($form['input'][$item]);