Commerce checkout, check if checkbox is checked

Question

I added a field to my commerce checkout form:

mymodule_form_alter(..) {
 ...
 if($form_id ="commerce_checkout_form") {
 $form['thisfield'] = array(
  '#type' => 'fieldset', 
  '#title' => t('Contact settings'), 
  '#weight' => 5, 
  '#collapsible' => TRUE, 
  '#collapsed' => FALSE,
 );

 $form['thisfield']['checkbox']= array (
   '#type' => 'checkboxes',
   '#options' => drupal_map_assoc(array(t('SAT'), t('ACT'))),
   '#title' => t('What standardized tests did you take?'),
   '#required' => TRUE,
 ),
 ....
 }
}

Now the form may not go to the next step if the checkbox is not checked. If i press the sumbit button now, i go to the next step with the error displayed that the field is requierd. So the error message appears, but the form still continues to the next step.

Now i don't really know how to keep the commerce form on the same step if the checkbox is not checked.

Answer 1

You shouldn't add the field directly to the checkout form, but rather create a new checkout pane and add the field to that.

e.g:

/**
 * Implements hook_commerce_checkout_pane_info
 */
function MODULE_commerce_checkout_pane_info() {
  $checkout_panes = array();

  $checkout_panes['contact_settings'] = array(
    'title' => t('Contact settings'), 
    'file' => 'includes/commerce_checkout.checkout_pane.inc', 
    'base' => 'MODULE_checkout_contact_settings_pane', 
    'page' => 'checkout', 
    'callbacks' => array('checkout_form_validate' => 'MODULE_checkout_contact_settings_pane_validate')
    'fieldset' => TRUE,
  );

  return $checkout_panes;
}

Put your form builder in includes/commerce_checkout.checkout_pane.inc > MODULE_checkout_contact_settings_pane

You can then use the Commerce API to validate your checkout form in

/**
 * Checkout pane validation for contact_settings
 */
function MODULE_checkout_contact_settings_pane_validate(&$form, &$form_state, $checkout_pane, $order) {

  // Do some validation tests here... omitted for brevity.
  if (empty($form_state['values']['thisfield'])) {
    drupal_set_message(t('Some validation error message'), 'warning');
    return FALSE;
  }

  return TRUE;

}

More info: hook_commerce_checkout_pane_info

Answer 2

Inside the form_alter you need to declare a custom validate function

$form['#validate'][] = 'my_module_custom_validate';

Inside the validate if the condition is not satisfied then generate form_set_error() which prevents it from submitting

function my_module_custom_validate(&$form,&$form_state) {

if ($form_state['values']['thisfield'] == 1) {
//condition for checked == true
form_set_error('thisfield', 'please untick to submit the form');
}

}