Expose labels of referenced entities

I like the change and it seems like it could reduce extra requests for each referenced entity to get the label.

Discuss whether we need a way to turn this off, to retain 100% BC.

I would hope we would not need another BC_* flag for this. I guess this something we didn't talk about in DrupalCon Vienna, whether API additions would need this BC_* flags.

I think if we can keep those to changes to existing field changes values that would be better and simpler.

We will need tests to prove these labels are actually returned, maybe just up the existing REST entity tests.

Added 'label' key to tests where needed.

This patch fixes media test fail.

Another problem I am seeing is the difference in how Config Entity(really non FieldableEntityInterface) is handled in hal_json format.

In the current patch NodeHalJsonAnonTest passes but NodeJsonAnonTest does not(there are other similar cases).

This is because they both rely on \Drupal\Tests\rest\Functional\EntityResource\Node\NodeResourceTestBase::getExpectedNormalizedEntity for the value of type which is an entity reference field with the target type node_type.

For json format the label 'article' is returned but for 'hal_json' not label is returned.

This because in \Drupal\hal\Normalizer\EntityReferenceItemNormalizer::normalize we have

// If this is not a content entity, let the parent implementation handle it,
    // only content entities are supported as embedded resources.
    if (!($target_entity instanceof FieldableEntityInterface)) {
      return parent::normalize($field_item, $format, $context);
    }

So for node_type it is handled by \Drupal\hal\Normalizer\FieldItemNormalizer which does not handle 'label'.

So maybe we I think should either handle the logic for Config entities in \Drupal\hal\Normalizer\EntityReferenceItemNormalizer also or we could change it to ContentEntityReferenceItemNormalizer and add a new ConfigEntityReferenceItemNormalizer. They would both have

protected $supportedInterfaceOrClass = 'Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem';

So we would have to supportsNormalization()in each normalizer to make sure they only covered the correct $target_entity values.

Of if changing the name of EntityReferenceItemNormalizer is a BC break we could just add the new ConfigEntityReferenceItemNormalizer but still use supportsNormalization() in both the new and existing normalizers.

Thank you for sharing your idea for improving Drupal.

We are working to decide if this proposal meets the Criteria for evaluating proposed changes. There hasn't been any discussion here for over 8 years which suggests that this has either been implemented or there is no community support. Your thoughts on this will allow a decision to be made.

Since we need more information to move forward with this issue, the status is now Postponed (maintainer needs more info). If we don't receive additional information to help with the issue, it may be closed after three months.

Thanks!