How do you reorder an entity reference revisions field during hook_node_presave?

Question

I am trying to reorder some paragraphs based on a text field within them on node save so the author does not need to maintain the alphabetical order manually, but when I save the node all values are lost. I tried matching the array from $node->get('field_paragraphs')->getValue(), but that does not seem to work.

function mymodule_node_presave(NodeInterface $node) {
  if ($node->bundle() == 'page' && $node>get('field_paragraphs')->count() > 1) {
    $values = $node->get('field_paragraphs')->getValue();
    $entities = $node->get('field_paragraphs')->referencedEntities();
    uasort($entities, function ($a, $b) {
      return Unicode::strcasecmp($a->get('field_text')->value, $b->get('field_text')->value);
    });

    $new_values = [];
    foreach ($entities as &$entity) {
      $id = $entity->id();
      $new_value = [
        'target_id' => $id,
        'target_revison_id' => $entity->getRevisionId(),
      ];
      $index = array_search($id, array_column($values, 'target_id'));
      if (FALSE !== $index && isset($values[$index]['subform'])) {
        $new_value['subform'] = $values[$index]['subform'];
      }
      $new_values[] = $new_value;
    }

    $node->set('field_paragraphs', $new_values);
  }
}

Answer 1

You don’t need to populate an array with the IDs of the referenced entities. You just need to use a single line, the following one.

$node->set('field_paragraphs', $entities);

The code you are using can be simplified to the following one.

function mymodule_node_presave(NodeInterface $node) {
  if ($node->bundle() == 'page' && $node>get('field_paragraphs')->count() > 1) {
    $entities = $node->get('field_paragraphs')->referencedEntities();
    uasort($entities, function ($a, $b) {
      return Unicode::strcasecmp($a->get('field_text')->value, $b->get('field_text')->value);
    });

    $node->set('field_paragraphs', $entities);
  }
}