Entity admin handlers

The Entity Admin Handlers module provides an out-of-the box admin UI for custom entity types whose configuration means that the admin UI code in Drupal core doesn't fit.

This reduces the need for boilerplate code to provide a UI to manage fields on the entity type and its bundles.

The following cases are provided for.

Single bundle entity type

This is for entity types that do not use bundles and in effect, have a single
bundle which typically has the same name as the entity type.

This is identical to the way the core user entity type works.

The handlers define a dummy route for Field UI module to hang its routes off.

Plain bundle entity type

This is for entity types that use multiple bundles, but do not have a config
entity type that defines the bundles (so for example, if the content entity type
is 'foo', there is no 'foo_type' entity type).

Such an entity type may have its bundles defined in hook_entity_bundle_info()
implementations, or have them derived from plugins using the Entity API contrib
module's bundle plugins functionality.

The handlers define a route that lists the bundles, and a dummy route for each
bundle for Field UI module to hang its routes off.

For each of these cases, the module provides:

• a route provider handler
• an entity links handler
• where required, a controller for any routes that are defined.

Requirements

This module expects the patch at https://www.drupal.org/project/drupal/issues/2976861 to be applied in order to provide menu, task, and action links. The routes will work without it, however.