How to get token of parent entity in paragraph?

Question

I have a paragraph, which is referenced by a node. Now I am trying to pass field values of node to the paragraph using tokens. I'm only aware of [paragraph:parent_id] and [paragraph:parent_type] but don't know how to get specific field values.

What I've tried so far without success:
[node:field_foo:value]
[paragraph:field_foo:value]
[paragraph:node:field_foo:value]
[paragraph:parent:field_foo:value]
[paragraph:parent:entity:field_foo:value]

The list of available tokens does not contain parent tokens. Is it even possible to get token of the parent entity? And if so, how?

Answer 1

There's nothing out of the box (see this issue for the details). Implementing your own token isn't too tricky.

I haven't had a chance to test this but I'm pretty sure it'll work:

function MODULE_token_info_alter(&$info) {
  $info['tokens']['paragraph']['parent_entity'] = [
    'name' => 'Parent entity',
    'description' => 'Parent entity of the paragraph',
  ];
}

function MODULE_tokens($type, $tokens, array $data, array $options, \Drupal\Core\Render\BubbleableMetadata $bubbleable_metadata) {
  $replacements = [];

  if ($type == 'paragraph' && $paragraph = $data['paragraph']) {
    $parent = $paragraph->getParentEntity();
    $bubbleable_metadata->addCacheableDependency($parent);

    foreach ($tokens as $name => $original) {
      if ($name == 'parent_entity') {
        $replacements[$original] = $parent->label();
      }
    }

    $token_service = \Drupal::token();
    if ($parent_entity_tokens = $token_service->findWithPrefix($tokens, 'parent_entity')) {
      $replacements += $token_service->generate($parent->getEntityTypeId(), $parent_entity_tokens, [$parent->getEntityTypeId() => $parent], $options, $bubbleable_metadata);
    }
  }

  return $replacements;
}

Answer 2

So with the newest version of Drupal 8 and Paragraphs, this is possible.

Looking at the tokens on /admin/help/token, there is a [paragraph:parent_entity] under the paragraphs section which is exactly what you need.

Example use case: to get the title of the parent node, I used [paragraph:parent_entity:title].