Drupal 8 / 9 migrate file / image fields to media fields

For my blog Drupal 6 to Drupal 9 Upgrade I finally needed to migrate regular image fields to media fields.

I first tried https://www.drupal.org/project/migrate_file_to_media but wasn't really happy and successful with that. Lots of problems for a relatively simple problem. So I thought about a simpler solution as I don't have many file duplicates in my case.

The result was a simple module to iterate all affected node types and programmatically create media entities from files. Afterwards set them as target for the prepared media fields on the same entity:

<?php

use \Drupal\file\FileInterface;
use \Drupal\media\Entity\Media;

/**
 * Defines the entities and source => target fields to run on.
 */
const FILEFILED_TO_MEDIAFIELD_NODE_TYPES = [
  'article' => ['field_image' => 'field_media_image'],
  'article' => ['field_image2' => 'field_media_image'],
  'page' => ['field_image' => 'field_media_image'],
];

/**
 * Creates a core media entity from a file entity.
 *
 * @param FileInterface $file
 * @param string $targetMediaBundle
 * @param string $targetMediaFieldName
 * @return Media
 */
function _filefield_to_mediafield_create_media_entity(FileInterface $file, $targetMediaBundle = 'image', $targetMediaFieldName = 'field_media_image'): Media {
  $media_entity = Media::create([
    'bundle' => $targetMediaBundle,
    'uid' => '1',
    'name' => !empty($file->alt) ? $file->alt : $file->label() . ', FID: ' . $file->id(),
    'status' => 1,
    $targetMediaFieldName => [
      'target_id' => $file->id(),
      'alt' => $file->alt,
    ],
  ]);
  $media_entity->save();
  return $media_entity;
}

/**
 * Copy in filefield_to_media.install CUSTOM DEFINED file field data to a defined media field.
 */
function filefield_to_mediafield_update_800x() {
  if (!empty(FILEFILED_TO_MEDIAFIELD_NODE_TYPES)) {
    foreach (FILEFILED_TO_MEDIAFIELD_NODE_TYPES as $node_type => $fields) {
      foreach ($fields as $sourceFileFieldName => $targetMediaFieldName) {
        $nodes = \Drupal::entityTypeManager()
          ->getStorage('node')
          ->loadByProperties(['type' => $node_type]);
        foreach ($nodes as $node) {
          if (!empty($node->{$sourceFileFieldName}->entity)) {
            try {
              $file = $node->{$sourceFileFieldName}->entity;
              $node->{$targetMediaFieldName}->entity = _filefield_to_mediafield_create_media_entity(
                $file
              );
              $node->save();
              \Drupal::logger('filefield_to_mediafield')->notice(
                'Copied file / image field file: "@file" in node "@node" from field "@sourceFileFieldName" to media field "@targetMediaFieldName".',
                ['@file' => $file->label() . ', FID:' . $file->id(), '@node' => $node->getTitle(), '@sourceFileFieldName' => $sourceFileFieldName, '@targetMediaFieldName' => $targetMediaFieldName]
              );
            } catch (Exception $e) {
              \Drupal::logger('filefield_to_mediafield')->error($e->getMessage());
            }
          }
        }
      }
    }
  }
}

It can be found here as sandbox project:

https://www.drupal.org/sandbox/anybody/3214753

Please help to improve it for other developers, perhaps by adding the drush command or creating a ui to select the entities, bundles, source and target fields? ;)

Thanks to https://chromatichq.com/insights/migrating-drupal-file-fields-media-ent… which was a good inspiration for the module, even if it was created for media_entity  at that time.