I have a webform that gets some hidden form fields set based on the referring URL. Within hook_form_alter, I can successfully set the hidden values with $form[elements][NAME]['#value'].

function MODULE_form_alter(&$form,\Drupal\Core\Form\FormStateInterface $form_state, $form_id) {

 //Get referring Program path/URL
 $previousUrl = \Drupal::request()->server->get('HTTP_REFERER');

 if ($form_id == FORM_ID) {

    $prog = getLeadProgramContact($previousUrl); 
    $form['elements']['referrer']['#value'] = $prog->field_email->value;
    $form['elements']['program_name']['#value'] = $prog->getName();

However, when the form gets submitted, it appears hook_form_alter is called again, breaking everything, since the referring URL is now itself.

How can I permanently set hidden field values on initial form render? Anything I try with hook_form_alter seems to fail. I have also tried "#default_value"

  • could you simply use a $_GET var ? is this a webform submission (as looks like it) ... if not have you thought of using "hook_entity_insert" ?
    – taggartJ
    Jun 13, 2018 at 23:53

1 Answer 1


Ok webforms are a bit tricky ... but this will work i don't really care to set hidden fields just set the data direct to the entity.

if this is not a multy step form you could probably ad another submit handler in your form alter aka ...

function MODULE_form_alter(&$form,\Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
   if ($form_id === FORM_ID) { 
     $submit[] = 'MODULE_form_alter_submit';
// then 
function MODULE_form_alter_submit(&$form,\Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
     // get the data you need.. via this ..
    $previousUrl = \Drupal::request()->server->get('HTTP_REFERER');
    $prog = getLeadProgramContact($previousUrl); 
    // or ($_GET) or session or cookie whatever you chose.. Then set    it 

    // GET the form Object.
    $webform_submission_object = $form_state->getFormObject();
    // GET the submission object.
    $webform_submission = $webform_submission_object->getEntity();
    // Optioanl default values if need to play with them .. 
    $orig_data = $webform_submission->getOriginalData();
    // set form state
    $form_state->setValue('referrer', $prog->...);
    // set submission field value.  
    $webform_submission->setElementData('referrer', $value);

    $form_state->setValue('program_name', $prog->...);
    $webform_submission->setElementData('program_name', $value);
    // Save it so it cant go away.

  • T: Tried this; still same deal, although it is updating the entity successfully. All the docs I have read say that hook_form_alter gets called "before a form is rendered." With Webform, it appears hook_form_alter gets called when submit is clicked, too. Jun 19, 2018 at 20:03
  • I refactored and is working now. Thanks, Taggart, for the insight! Jun 20, 2018 at 15:08

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