Expose the computed "group" asset field to Views.

modules/asset/group/farm_group.module

@@ -29,6 +29,21 @@ function farm_group_entity_base_field_info(EntityTypeInterface $entity_type) {
   }
 }
 
+/**
+ * Implements hook_views_data_alter().
+ */
+function farm_group_views_data_alter(array &$data) {
+
+  // Add the computed group membership field to assets.
+  $data['asset']['group'] = [
+    'title' => t('Current group'),
+    'field' => [
+      'id' => 'asset_group',
+      'field_name' => 'group',
+    ],
+  ];
+}
+
 /**
  * Implements hook_views_pre_view().
  */

modules/asset/group/src/Plugin/views/field/AssetGroup.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Drupal\farm_group\Plugin\views\field;
+
+use Drupal\views\Plugin\views\field\EntityField;
+
+/**
+ * A field that displays asset group.
+ *
+ * @ingroup views_field_handlers
+ *
+ * @ViewsField("asset_group")
+ */
+class AssetGroup extends EntityField {
+
+}