How can I dynamically get the fields on an image media bundle?

Question

What’s the correct way to get all of the key/values for a bundle on a media entity?

I am trying to create a media entity programmatically and I need to get all of the fields on the image bundle. I am not sure how to get the image bundle ID either.

In other words, I’d like the module I'm working on to be a bit more generic and reusable as I’ve seen the image bundle have different names depending on the installation.

Here’s what I have so far but the two main problems I see are that the image bundle ID can change and the field names on the bundle can be different.

   $entity = $this->createFile(
      $uri,
      $file[0]['filename'],
      $file[0]['filesize'],
      $this->currentUser
    );
    $entity->setPermanent();
    $entity->save();
    // Save media entity
    $media = [
      'bundle' => 'image',
      'uid' => $this->currentUser->id(),
      'status' => 1,
      'image' => [
        'target_id' => $entity->id(),
        'alt' => t(basename($file[0]['filename'])),
        'title' => t(basename($file[0]['filename'])),
      ],
    ];
    $image = $this->entityTypeManager->getStorage('media')->create($media);
    $image->save();

I'd like to be able to get the image bundle and dynamically figure out whichever field has the target_id and then assign the previously created file entity to that. I do not know how to get the image bundle schema, array signature, in order to traverse the key/values to find the target_id

Answer 1

You can traverse the field definitions of the media bundle image and look for a field with the type image:

$fields = \Drupal::service('entity_field.manager')->getFieldDefinitions('media', 'image');
foreach ($fields as $key => $field) {
  if ($field->getType() === 'image') {
    // found image field $key
  }
}

To get all media bundles:

$bundles = \Drupal::service('entity_type.bundle.info')->getBundleInfo('media');