Issue #2715589 by claudiu.cristea, jibran, amateescu: Remove stale 'handler_submit' setting from the ER field configs

core/modules/field/field.post_update.php

@@ -6,10 +6,10 @@
  */
 
 use Drupal\Core\Entity\Entity\EntityFormDisplay;
+use Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\field\Entity\FieldConfig;
 
-
 /**
  * Re-save all field storage config objects to add 'custom_storage' property.
  */
@@ -59,3 +59,26 @@ function field_post_update_email_widget_size_setting() {
 
   return t('The new size setting for email widgets has been added.');
 }
+
+/**
+ * Remove the stale 'handler_submit' setting for entity_reference fields.
+ */
+function field_post_update_remove_handler_submit_setting() {
+  $config = \Drupal::configFactory();
+  /** @var \Drupal\Core\Field\FieldTypePluginManager $field_type_manager */
+  $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
+
+  // Iterate on all field configs.
+  foreach ($config->listAll('field.field.') as $field_id) {
+    $field = $config->getEditable($field_id);
+    $class = $field_type_manager->getPluginClass($field->get('field_type'));
+
+    // Deal only with entity reference fields and descendants.
+    if ($class === EntityReferenceItem::class || is_subclass_of($class, EntityReferenceItem::class)) {
+      if ($field->get('settings.handler_submit')) {
+        // Remove 'handler_settings' from settings.
+        $field->clear('settings.handler_submit')->save();
+      }
+    }
+  }
+}

core/modules/field/tests/fixtures/update/drupal-8.remove_handler_submit_setting-2715589.php

@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * @file
+ * Provides necessary database additions for testing
+ * field_post_update_remove_handler_submit_setting()
+ */
+
+use Drupal\Core\Database\Database;
+
+$connection = Database::getConnection();
+
+$config = unserialize($connection->select('config', 'c')
+  ->fields('c', ['data'])
+  ->condition('collection', '')
+  ->condition('name', 'field.field.node.article.field_tags')
+  ->execute()
+  ->fetchField());
+
+$config['settings']['handler_submit'] = 'Change handler';
+
+$connection->update('config')
+  ->fields(['data' => serialize($config)])
+  ->condition('collection', '')
+  ->condition('name', 'field.field.node.article.field_tags')
+  ->execute();

core/modules/field/tests/src/Functional/Update/FieldUpdateTest.php

@@ -36,6 +36,7 @@ class FieldUpdateTest extends UpdatePathTestBase {
     $this->databaseDumpFiles = [
       __DIR__ . '/../../../../../system/tests/fixtures/update/drupal-8.bare.standard.php.gz',
       __DIR__ . '/../../../fixtures/update/drupal-8.views_entity_reference_plugins-2429191.php',
+      __DIR__ . '/../../../fixtures/update/drupal-8.remove_handler_submit_setting-2715589.php',
     ];
   }
 
@@ -141,4 +142,21 @@ class FieldUpdateTest extends UpdatePathTestBase {
     $this->assertEqual(in_array('entity_reference', $dependencies['module']), $present);
   }
 
+  /**
+   * Tests field_post_update_remove_handler_submit_setting().
+   *
+   * @see field_post_update_remove_handler_submit_setting()
+   */
+  public function testEntityReferenceFieldConfigCleanUpdate() {
+    $field_config = $this->config('field.field.node.article.field_tags');
+    // Check that 'handler_submit' key exists in field config settings.
+    $this->assertEquals('Change handler', $field_config->get('settings.handler_submit'));
+
+    $this->runUpdates();
+
+    $field_config = $this->config('field.field.node.article.field_tags');
+    // Check that 'handler_submit' has been removed from field config settings.
+    $this->assertArrayNotHasKey('handler_submit', $field_config->get('settings'));
+  }
+
 }