Allow config entity references

Just confirmed from @dawehner that we don't need the views integration for this as well.

Thank you for working on this.
We need following test cases and please create a new test file.

1. Config entity only configurable DER field.
2. Content entity and config entity configurable DER field.
3. Config entity only basefield DER field.
4. Config entity only revisonable basefield DER field.
5. Content entity and config entity basefield DER field.
6. Content entity and config entity revisonable basefield DER field.

For last four you can update dynamic_entity_reference_entity_test_entity_base_field_info with states.

As per #4 we don't want to expose it in field config settings form for configurable fields so just add some asserts to existing UI test to make sure it is not happening.

We also need some UI tests for autocomplete and autocreate just like \Drupal\Tests\dynamic_entity_reference\Functional\DynamicEntityReferenceTest

We also have to update \Drupal\dynamic_entity_reference\Plugin\Field\FieldType\DynamicEntityReferenceItem::defaultFieldSettings.

Thank you, this's some great work.
Sorry, I missed two test cases:

1. string id content entity and config entity.
2. string id content entity, int id content entity and config entity.

Only remaining things are

We also need some UI tests for autocomplete and autocreate just like \Drupal\Tests\dynamic_entity_reference\Functional\DynamicEntityReferenceTest

These should be specfic to config entity reference.

We also have to update \Drupal\dynamic_entity_reference\Plugin\Field\FieldType\DynamicEntityReferenceItem::defaultFieldSettings.

This is still pending.

1. +++ b/src/Plugin/Field/FieldType/DynamicEntityReferenceItem.php
   @@ -510,13 +515,21 @@ class DynamicEntityReferenceItem extends EntityReferenceItem {
   +  public static function getTargetTypes($settings, $include_configuration_entities = TRUE) {
   

   I think the second param should be FALSE by default but if making it TRUE makes the changes minimum then it's alright.

2. +++ b/tests/src/Kernel/DynamicEntityReferenceConfigEntityTest.php
   @@ -0,0 +1,345 @@
   +      'settings' => [],
   

   We should add some settings here.

3. +++ b/tests/src/Kernel/DynamicEntityReferenceConfigEntityTest.php
   @@ -0,0 +1,345 @@
   +  public function testBaseField() {
   ...
   +  public function testRevisionableBaseField() {
   ...
   +  public function testMixedBaseField() {
   ...
   +  public function testMixedRevisionableBaseField() {
   

   Let's move basefield tests to separate file.

Let's add a core bug if there is not one yet. #2405467: Add EntityType and Bundle constraint on entity property of DynamicEntityReferenceItem is in and I think we might have to adapt here.

That was actually added in #17.

Sorry, it was a one line thing so I missed it in the patch. :)
Thank you for the awsome work. This needs a reroll after #2405467: Add EntityType and Bundle constraint on entity property of DynamicEntityReferenceItem.

+1 to #26. Let's get this in.

I think we are almost ready. Just wait for #2729463: List of view_modes is empty in dynamic_entity_reference_entity_view formatter then we can commit this. #2458353: DER fields should add selection handler config dependencies will become a bug after this so should we move it here? Just few minor observations and thanks for the new patch and tests.

1. +++ b/dynamic_entity_reference.views.inc
   @@ -159,7 +159,7 @@ function dynamic_entity_reference_views_data() {
   -      $targets = array_intersect(DynamicEntityReferenceItem::getTargetTypes($field->getSettings()), array_keys($sql_entity_types));
   +      $targets = array_intersect(DynamicEntityReferenceItem::getTargetTypes($field->getSettings(), TRUE), array_keys($sql_entity_types));
   

   Do we need this? I don't think so. views data for config entities, it doesn't make sense unless I'm missing something?

2. +++ b/src/Plugin/Field/FieldType/DynamicEntityReferenceItem.php
   @@ -56,6 +56,10 @@ class DynamicEntityReferenceItem extends EntityReferenceItem {
        $labels = \Drupal::service('entity_type.repository')->getEntityTypeLabels(TRUE);
        $options = $labels[(string) t('Content', [], ['context' => 'Entity type group'])];
   ...
   +    // Add configuration entities.
   +    $options += $labels[(string) t('Configuration', [], ['context' => 'Entity type group'])];
   

   We can just use labels as is without passing TRUE to getEntityTypeLabels().

Thank you! for adding #2458353: DER fields should add selection handler config dependencies into this. #2729463: List of view_modes is empty in dynamic_entity_reference_entity_view formatter is fixed now. It maybe needs a reroll. Let's get this fixed as well.

Thanks! committed to 8.x-2.x