How can I save and exit from the middle of editing an already completed multipage webform submission?

Question

I've got a multipage webform I'm letting users edit after they submit. There are many pages, and I don't want to force the user to go all the way to the last page to save. Is there a way to submit/save the form either with a Save Draft button, or when they use the prev/next buttons? Or is there a way to programmatically save the edited form ? That would also work.

This question is about editing a completed submission, not creating a new submission.

I've tried adding the submit button to every page, but it seems to function like a next button. If I set rebuild to false, the I can exit the edit process where I want, but the changes are not saved.

I've also tried manually adding a save draft button copied from the webform submission form, but that also did not work, failing the way the submit button did.

Answer 1

I was able to get this to work like so:

In a form alter, make the Submit button visible, and change the name.

   if (stristr($form_id, 'edit_form') !== FALSE) {
    $form["actions"]["submit"]['#value'] = t('Save & Exit');
    $form["actions"]["submit"]["#access"] = TRUE;
    $form["actions"]["submit"]["#_webform_access"] = TRUE;
    // Add a custom submit function so we can redirect the edit form.
    $form['actions']['submit']['#submit'][] = 'mymodule_webform_submission_form_submit';
    $form['actions']['submit']['#validate'][] = 'mymodule_webform_submission_form_validate';

  }

Next, in the custom validation function:

  // If this is the edit form, and the submit button is the trigger, always
  // do the final submit by setting the current wizard page to the confirmation
  // page.
  $trigger = $form_state->getTriggeringElement();
  if ($trigger["#id"] == 'edit-actions-submit' &&
    stristr($form['form_id']['#value'], 'edit_form') !== FALSE) {
    $form_state->set('current_page', 'webform_confirmation');
  };

Finally, in the custom submit function:

$build = $form_state->getBuildInfo();
$callback_object = $build['callback_object'];
$entity = $callback_object->getEntity();
$source = $entity->getSourceEntity();
if (!is_null($source)) {
  $nid = $entity->getSourceEntity()->id();
  $form_state->setRedirect('entity.node.canonical', ['node' => $nid]);
  $form_state->setRebuild(FALSE);
  \Drupal::messenger()->addStatus("Your work has been saved.");
}

While this answers my question, it leaves me having to deal with potential errors from conditionally required fields affected by whatever changes the user is trying to save.