Hide entity type selector from default widget when there is only one target type.

lol @ last patch.

+++ b/src/Plugin/Field/FieldWidget/DynamicEntityReferenceWidget.php
@@ -97,7 +97,7 @@
-        '#type' => 'value',
+        '#type' => 'hidden',

'value' is safer than 'hidden'. See https://api.drupal.org/api/drupal/developer%21topics%21forms_api_referen... and https://api.drupal.org/api/drupal/developer%21topics%21forms_api_referen... for more details.

Great work @JeroenT. Just one point after that I think it is ready.

+++ b/tests/src/Functional/DynamicEntityReferenceWidgetTest.php
@@ -113,7 +113,6 @@ class DynamicEntityReferenceWidgetTest extends BrowserTestBase {
-      $field_name . '[0][target_type]' => $referenced_node->getEntityTypeId(),

Let's assert selectNotExists or something similar to make sure it is not on the page.

I have done manual testing. It works great. This is RTBC for me. Can you please upload the patch for 8.x-2.x branch?

Thanks for the patch.

+++ b/tests/src/Functional/DynamicEntityReferenceWidgetTest.php
@@ -116,6 +116,9 @@
+    // Only 1 target_type is configured, so this field is not available on the
+    // node add/edit page.
+    $assert_session->fieldNotExists($field_name . '[0][target_type]');

Seems like we are missing this from 2.x patch.

+++ b/tests/src/Functional/DynamicEntityReferenceWidgetTest.php
@@ -134,6 +132,19 @@ class DynamicEntityReferenceWidgetTest extends BrowserTestBase {
+    $field_config = FieldConfig::loadByName('node', 'reference_content', $field_name);
+    $field_config_settings = $field_config->getSettings();
+    $field_config->setSetting('config_test', [
+      'handler' => 'default',
+      'handler_settings' => [],
+    ]);
+    $field_config->save();
+
+    $field_storage_config = FieldStorageConfig::loadByName('node', $field_name);
+    $field_storage_config_settings = $field_storage_config->getSettings();
+    $field_storage_config->setSetting('entity_type_ids', ['node', 'config_test']);
+    $field_storage_config->save();
+

@@ -144,6 +155,9 @@ class DynamicEntityReferenceWidgetTest extends BrowserTestBase {
+    // Multiple target_types are configured, so this field should be available
+    // on the node add/edit page.
+    $assert_session->fieldExists($field_name . '[0][target_type]');

@@ -153,6 +167,11 @@ class DynamicEntityReferenceWidgetTest extends BrowserTestBase {
+
+    $field_config->setSettings($field_config_settings);
+    $field_config->save();
+    $field_storage_config->setSettings($field_storage_config_settings);
+    $field_storage_config->save();

I think tests changes from #2829602: Disable optgroup in select list when only 1 target_bundle is available. also got into this patch other then that this is RTBC.

Oh! got it. Thanks for explanation. This is also ready.

I committed #22 to 8.x-2.x.

Pushed to 8.x-1.x