Getting existing fields in hook_entity_bundle_field_info()

Question

I have custom fields that I need to add to specific entity types and bundles with hook_entity_bundle_field_info(). However, I have to decide on which one to add depending on already existing fields, hence I need to ask for those. The hook function only receives the base field definitions passed as an argument, not the bundle fields. And, unfortunately, it seems I cannot use \Drupal::service('entity_field.manager')->getFieldDefinitions() from inside hook_entity_bundle_field_info() because it leads to an out-of-memory error, as it very probably calls itself repeatedly.

How can I make decisions depending on the presence and settings (eg. enabled status) of already existing fields?

Answer 1

To add a new field basing on the existing fields, the code needs to use hook_entity_bundle_field_info_alter(&$fields, EntityTypeInterface $entity_type, $bundle), which receives the list of the already defined fields (an array) to which new fields can be added, not hook_entity_bundle_field_info().

The Field module implements field_entity_bundle_field_info() because it does not need to add fields basing on the existing ones. It just adds its own fields, without checking which fields already exist.

Answer 2

I found the core field module to use a direct entity query approach like:

$ids = \Drupal::entityQuery('field_config')
  ->condition('id', $entity_type->id() . '.' . $bundle . '.', 'STARTS_WITH')
  ->execute();
$field_configs = FieldConfig::loadMultiple($ids);

It looks like the actual way forward.