entity_form how to programmatically add references and update the form visually (entity_browser)

Question

I´m having an fieldable entity with a reference field to paragraphs field_paragraphs and a paragraph_type with a reference field to content_type event field_events.

What i am trying in the entity form is to have a button in the paragraph_type event subform which on click prefills the field_events of the paragraph_type with content. The form display of field_events uses an entity_browser to let the user also manually choose or deselect programmatically added events and i guess this is where I am stuck.

I think i am pretty close to the solution, let me try to describe:

When clicking the button, the added events are not visible, if I use the entity_browser now to insert an event, all the events that i programmatically added get displayed.

So I somehow need to tell the entity_browser in my callback to return the updated list, i guess (I´m a Drupal beginner, so please go easy on me) But I have no clue how to do so, also i think it should be possible without doing so? I mean just add the references and let the "form rebuild independently of the form display" ... I dont know, here is the code so far:

/**
 * Implements hook_field_widget_WIDGET_TYPE_form_alter().
 */
function module_field_widget_paragraphs_form_alter(&$element, &$form_state, $context) {

  switch ($element['#paragraph_type']) {
   case 'events':

      $replace_id = $element['subform']['field_events']['widget']['#id'];

      $element["subform"]['add_tomorrows_events_button'] = [
        '#type' => 'button',
        '#attributes' => [
          'name' => 'add_tomorrows_events',
        ],
        '#value' => t('Add tomorrows events'),
        '#ajax' => [
          'callback' => 'module_insert_tomorrows_events_into_paragraph_events',
          'wrapper' => $replace_id,
          'method' => 'replace',
          'event' => 'click',
        ]
      ];

     break;

   default:
     // code...
     break;
 }

}

---

/**
 * Ajax callback.
 */
function module_insert_tomorrows_events_into_paragraph_events( &$form, FormStateInterface &$form_state) {

  /* Get the index of the paragraph in field_paragraphs */
  $triggering_element = $form_state->getTriggeringElement();
  $paragraph_index = $triggering_element["#parents"][1];


  /* For now just try to add 10 events */
  $results = \Drupal::entityQuery('node')
  ->condition('type', 'event')
  ->range(0, 10)
  ->execute();

  /* Here I´m trying to build up the string like it is in the target_id key of the widget 
     e.G "node:3213 node:54354 node:432423"
  */
  $target_ids = "";
  foreach ($results as $res) {
    $target_ids .= " node:".$res;
  }


  

  $form["field_paragraphs"]['widget'][$paragraph_index]["subform"]["field_events"]["widget"]["target_id"]['#value'] = $target_ids;

  /* just other stuff i tried */
  /*$form["field_paragraphs"]['widget'][$paragraph_index]["subform"]["field_events"]["widget"]["target_id"]['#default_value'] = $target_ids;*/
  /*  $form_state->setValue(['field_paragraphs', $paragraph_index, 'subform', 'field_events', 'target_id'], $target_ids);
  $form_state->setRebuild(true);
    */
/* tried to update the EB but `current` is not updated :/
   $t = EntityReferenceBrowserWidget::updateWidgetCallback($form, $form_state); 
   return $t["field_paragraphs"]["widget"][$paragraph_index]["subform"]["field_events"]["widget"];
*/




  return $form["field_paragraphs"]['widget'][$paragraph_index]["subform"]["field_events"]["widget"];
}

TL;DR: The events get added but the entity_form/entity_browser is not updated visually, after using the entity_browser all programmatically added events get displayed, how to display them in the first place?

Answer 1

I got it working, i´m sharing this if anybody stumbles across the same, in the end it was trivial with using ReplaceCommand and InvokeCommand

function module_field_widget_paragraphs_form_alter(&$element, &$form_state, $context) {
  switch ($element['#paragraph_type']) {
    case 'paragraph_events':

      // Add the button only if the paragraph-subform is expanded.
      if ($element['top']['summary']['fields_info']['#expanded']) {
        $element["subform"]['add_tomorrows_events_button'] = [
          '#type' => 'button',
          '#attributes' => [
            'name' => 'add_tomorrows_events',
          ],
          '#value' => t('insert tomorrows events'),
          '#ajax' => [
            'callback' => '_module_insert_tomorrows_events_into_paragraph_events',
            'event' => 'click',
          ],
        ];
      }

      break;


      ...

and the callback

function _module_insert_tomorrows_events_into_paragraph_events(&$form, FormStateInterface $form_state): AjaxResponse {

  $triggering_element = $form_state->getTriggeringElement();
  $paragraph_index = $triggering_element["#parents"][1];


  // Load results from view.
  $view = Views::getView('events');
  if (!$view || !array_key_exists('tomorrows_events', $view->storage->get('display'))) {
    return "view \"events\" or display \"tomorrows_events\" is missing";
  }

  $view->setDisplay('tomorrows_events');
  $view->execute();
  $results = $view->result;

  $target_ids = "";
  foreach ($results as $res) {
    $target_ids .= " node:" . $res->nid;
  }


  $form["field_paragraphs"]['widget'][$paragraph_index]["subform"]["field_events"]["widget"]["target_id"]['#value'] = $target_ids;
  $response = new AjaxResponse();

  $sel = '#' . $form["field_paragraphs"]["widget"][$paragraph_index]["subform"]['field_events']['widget']['target_id']["#id"];
  $response->addCommand(new ReplaceCommand($sel, $form["field_paragraphs"]["widget"][$paragraph_index]["subform"]['field_events']['widget']['target_id']));
  $response->addCommand(new InvokeCommand($sel, 'trigger', ['entity_browser_value_updated']));

  return $response;

}