Clean up \Drupal\jsonapi\LinkManager\LinkManager(Interface)

3. I didn't think about the collection aspect. That's a good point. We should then at least rename it to getCurrentRequestLink().

5. See 3.

I see you +1'd #2758897: Move rest module's "link manager" services to serialization module at comment 12.

So, rolled a patch for that: #2758897-13: Move rest module's "link manager" services to serialization module.

Indeed it finally landed :)

IS updated.

We'll still need to figure out how to proceed here.

Damn, we'll need #2353611: Make it possible to link to an entity by UUID for that.

Looking at this again.

Core's status

So core has this:

1. interface LinkManagerInterface extends TypeLinkManagerInterface, RelationLinkManagerInterface {}

2. interface RelationLinkManagerInterface extends ConfigurableLinkManagerInterface {
     public function getRelationUri($entity_type, $bundle, $field_name, $context = array());
     public function getRelationInternalIds($relation_uri);
   }
   

3. interface TypeLinkManagerInterface extends ConfigurableLinkManagerInterface {
     public function getTypeUri($entity_type, $bundle, $context = array());
     public function getTypeInternalIds($type_uri, $context = array());
   }

4. interface ConfigurableLinkManagerInterface {
     public function setLinkDomain($domain);
   }
   

It used to live in the REST module, since #2758897: Move rest module's "link manager" services to serialization module all of that lives in the serialization module.

But… all this linkmanager stuff is only ever used by the HAL module's normalizers! And all of it is tied to entity types!!! So it's not at all about generic resources, as one would expect. It all only works for entities. So it's actually EntityTypeLinkManagerInterface and EntityRelationLinkManagerInterface, even if it doesn't want to admit that.

So that's two ways in which the link manager is utterly and totally flawed. It'd have been fine if this was the implementation, but the fact that this is an interface means that we're shackled to this API until Drupal 9. We can't even actually sanely expand it with additional kinds of links (because interface LinkManagerInterface extends TypeLinkManagerInterface, RelationLinkManagerInterface {}).

What an utter fail. :(

And then if I go look at where they're used, for example I see this in \Drupal\hal\Normalizer\ContentEntityNormalizer::normalize():

    /** @var $entity \Drupal\Core\Entity\ContentEntityInterface */
    $normalized = array(
      '_links' => array(
        'self' => array(
          'href' => $this->getEntityUri($entity),
        ),
        'type' => array(
          'href' => $this->linkManager->getTypeUri($entity->getEntityTypeId(), $entity->bundle(), $context),
        ),
      ),
    );

So we get that "type" link from the link manager, but not the "self" link. Sigh. :(

JSON API's status

The JSON API contrib module has this:

class LinkManager {
  public function getEntityLink($entity_id, ResourceType $resource_type, array $route_parameters, $key);
  public function getRequestLink(Request $request, $query = NULL);
  public function getPagerLinks(Request $request, array $link_context = []);
}

It does not extend the existing link manager, because that used to live in REST (which JSON API does not depend on) until just a few weeks ago. However, none of the links in the link manager would actually even be helpful! They all only make sense for the HAL normalization! And even then only for entities!

getEntityLink() clearly fulfills the exact same purpose as this in the HAL module: 'href' => $this->getEntityUri($entity),. So we could add a getEntityLink() method to the serialization module's link manager, which could then also be used by HAL's normalizers… but it wouldn't adequately address JSON API's entity link needs, because that $key parameter there allows also e.g. the "related" link for an entity to be generated.

Conclusion

1. JSON API should indeed have its own link manager.
2. The Serialization module's link manager is misplaced: it actually belongs in the HAL module! (Also proven by the fact that $this->linkManager appears 0 times in core/modules/serialization and 6 times in core/modules/hal.)

2. The Serialization module's link manager is misplaced: it actually belongs in the HAL module! (Also proven by the fact that $this->linkManager appears 0 times in core/modules/serialization and 6 times in core/modules/hal.)

This resulted in me opening #2854830: Move rest/serialization module's "link manager" services to HAL module.

So, based on:

1. the analysis in #12, which shows that \Drupal\jsonapi\LinkManager\LinkManager cannot possibly build on top of the Serialization module's LinkManager
2. the fact that \Drupal\jsonapi\LinkManager\LinkManager is marked as @internal

I'm closing this. The code is good enough for now. There are no abstractions/concepts that this should be building on top of, because they're deeply flawed (as #12 demonstrated). Therefore there is nothing we can do right now, and we do continue to have the ability to make this code better in the future.