Create any number of paragraph fields in a multiple value field on node create form

Question

I have a paragraphs field that takes a term reference.

I need to count how many terms there are for a specific vocabulary and then create that many instance of the paragraphs multiple value field for when creating a node of a certain type. Can this be done with Hook_form_alter ?

It is important that these fields are loaded when the node creation form is loaded rather than the user having to click add more

Any help would be greatly appreciated

I have tried this but when saving the node it doesn't save the new fields

function hook_form_alter(&$form, $form_state, $form_id) {

  if ($form_id == 'my_form') {

  $item = $form['field_features']['widget']['0'];

  // get taxonomy terms
  $query = \Drupal::entityQuery('taxonomy_term');
  $query->condition('vid', "my_voc");
  $tids = $query->execute();
  $terms = \Drupal\taxonomy\Entity\Term::loadMultiple($tids);

  $count = count($terms);

  $i = '1';
  foreach($terms as $term){
    $form['field_features_para']['widget'][$i] = $item;
    $form['field_features_para']['widget'][$i]['#delta'] = $i;
    $form['field_features_para']['widget'][$i]['#weight'] = $i;
    $i ++;
  }
 }
}

Answer 1

Instead of adding the multi value field items after the form is built you can try to do this on the entity before the form is built:

/**
 * Implements hook_ENTITY_TYPE_create() for 'node'.
 */
function mymodule_node_create(\Drupal\node\NodeInterface $node) {

  if ($node->getType() == 'my_content_type') {
    // get taxonomy terms
    $query = \Drupal::entityQuery('taxonomy_term');
    $query->condition('vid', "my_voc");
    $tids = $query->execute();
    $terms = \Drupal\taxonomy\Entity\Term::loadMultiple($tids);

    $count = count($terms);

    $i = '1';
    foreach ($terms as $term) {
      $paragraph = \Drupal::entityTypeManager()->getStorage('paragraph')->create([
        'title' => 'Paragraph ' . $i,
        'type' => 'my_paragraph_type',
         // more field data
      ]);
      $node->field_features_para[] = $paragraph;
      $i++;
    }
  }

}