Get the draft data in the webform hook_form_FORM_ID_alter()

Question

I'm building a multi page webform in Drupal 8 as shown below

(1) Consent to ask questions >>> (2) Chekcing eligiblity >>> (3) Consent to Participate >>> (4) Base line info >>> (5) Complete

multipage webform

In the 2nd page (Checking eligibility) as soon as the user clicks on Next Page > button, I need to validate the submitted values (which contains several radio buttons) and assess the user whether he is eligible to participate in a survey or not.

/*
 * hook_form_FORM_ID_alter()
 */
function webform_form_webform_submission_registration_content_node_77_form_alter(&$form, FormStateInterface $form_state, $form_id) {
    ...
    if($form_id == 'webform_submission_registration_content_node_77_form')
    {
        $form['#submit'][] = 'webform_webform_submit_handler';

    }

}

function webform_webform_submit_handler($form, &$form_state) {
    /* This is not displaying any submited values mostly because I haven't clicked on Sumbit button yet */
       dpm($form_state['values']); 
}

src: https://www.drupal.org/node/2634266

Is there any way to get the Form's draft values before submission? Any better approach to process the values within the page(form) itself? Any help much appreciated.

Answer 1

As jrockowitz suggested, the best way to get the webform's data and processing it is, to create custom WebformHandler. Please refer "Creating a custom webform handler plugin for drupal 8" section here for more details.