Use events to handle field exports

modules/mukurtu_export/mukurtu_export.services.yml

@@ -1,4 +1,9 @@
 services:
   plugin.manager.mukurtu_exporter:
     class: Drupal\mukurtu_export\MukurtuExporterPluginManager
-    parent: default_plugin_manager
+    parent: default_plugin_manager
+  mukurtu_export.csv_field_export_event_subscriber:
+    class: Drupal\mukurtu_export\EventSubscriber\CsvEntityFieldExportEventSubscriber
+    arguments: ['@messenger']
+    tags:
+      - { name: event_subscriber }

modules/mukurtu_export/src/Event/EntityFieldExportEvent.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace Drupal\mukurtu_export\Event;
+
+use Drupal\Component\EventDispatcher\Event;
+use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * Event when an entity field is being exported.
+ */
+class EntityFieldExportEvent extends Event
+{
+  const EVENT_NAME = 'mukurtu_export_entity_field_export';
+
+  /**
+   * The exporter plugin ID.
+   *
+   * @var string
+   */
+  public $exporter_id;
+
+  /**
+   * The entity.
+   *
+   * @var \Drupal\Core\Entity\EntityInterface
+   */
+  public $entity;
+
+  /**
+   * The field name.
+   *
+   * @var string
+   */
+  public $field_name;
+
+  /**
+   * The field value to export.
+   *
+   * @var mixed
+   */
+  protected $value;
+
+  public function __construct($exporter_id, EntityInterface $entity, $field_name)
+  {
+    $this->exporter_id = $exporter_id;
+    $this->entity = $entity;
+    $this->field_name = $field_name;
+    $this->value = [];
+  }
+
+  public function getValue()
+  {
+    return $this->value;
+  }
+
+  public function setValue($value)
+  {
+    $this->value = $value;
+    return $this;
+  }
+
+}

modules/mukurtu_export/src/EventSubscriber/CsvEntityFieldExportEventSubscriber.php

@@ -0,0 +1,41 @@
+<?php
+
+namespace Drupal\mukurtu_export\EventSubscriber;
+
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Drupal\mukurtu_export\Event\EntityFieldExportEvent;
+
+class CsvEntityFieldExportEventSubscriber implements EventSubscriberInterface
+{
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents()
+  {
+    return [
+      EntityFieldExportEvent::EVENT_NAME => ['exportField', -100],
+    ];
+  }
+
+  public function exportField(EntityFieldExportEvent $event)
+  {
+    if ($event->exporter_id != 'csv') {
+      return;
+    }
+    $entity = $event->entity;
+    $field_name = $event->field_name;
+
+    $field = $entity->get($field_name);
+    $fieldType = $field->getFieldDefinition()->getType() ?? NULL;
+
+    $values = $entity->get($field_name)->getValue();
+    $exportValue = [];
+    foreach ($values as $value) {
+      $exportValue[] = is_array($value) ? reset($value) : $value;
+    }
+
+    $event->setValue($exportValue);
+  }
+
+}

modules/mukurtu_export/src/Plugin/MukurtuExporter/CSV.php

@@ -6,6 +6,7 @@
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\File\FileSystemInterface;
+use Drupal\mukurtu_export\Event\EntityFieldExportEvent;
 use Exception;
 
 /**
@@ -32,6 +33,7 @@ public function defaultConfiguration()
               'digital_heritage' => [
                 'title' => 'Title',
                 'field_description' => "Description",
+                'field_media_assets' => "Media Assets",
                 'nid' => 'ID',
                 'uuid' => 'UUID',
               ],
@@ -272,11 +274,20 @@ public static function batchCompleted(&$context)
    */
   public static function export(EntityInterface $entity, &$context)
   {
+    //$moduleHandler = \Drupal::moduleHandler();
+    $event_dispatcher = \Drupal::service('event_dispatcher');
+
     // Get mapping to determine what fields to export.
+    $multiValueDelimiter = '||';
     $field_mapping = $context['results']['settings']['field_mapping'];
     $export = [];
     foreach ($field_mapping[$entity->getEntityTypeId()][$entity->bundle()] as $field_name => $label) {
-      $export[] = $entity->get($field_name)->getValue()[0]['value'] ?? "";
+      $event = new EntityFieldExportEvent('csv', $entity, $field_name);
+      $event_dispatcher->dispatch($event, EntityFieldExportEvent::EVENT_NAME);
+      $exportValue = $event->getValue();
+
+      //$moduleHandler->alter("exporter_csv_field_{$fieldType}", $exportValue, $entity, $field_name);
+      $export[] = implode($multiValueDelimiter, $exportValue);
     }
     return $export;
   }