Where can I find all form display options types for custom entity fields?

Question

I created a custom entity with drupal generate:entity:content.

I am adding fields in the baseFieldDefinitions method of the entity class.

Below is what drupal console generates by default for the name field.

Where I can find a list of all possible type values for ->setDisplayOptions('form'). For example, the field below uses string_textfield.

public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
    ...
    $fields['name'] = BaseFieldDefinition::create('string')
      ->setLabel(t('Name'))
      ->setDescription(t('The name of the entity.'))
      ->setSettings([
        'max_length' => 50,
        'text_processing' => 0,
      ])
      ->setDefaultValue('')
      ->setDisplayOptions('view', [
        'label' => 'above',
        'type' => 'string',
        'weight' => -4,
      ])
      ->setDisplayOptions('form', [
        'type' => 'string_textfield',
        'weight' => -4,
      ])
      ->setDisplayConfigurable('form', TRUE)
      ->setDisplayConfigurable('view', TRUE);

Answer 1

Those are field widget plugin IDs.

You can get all of those by querying the field widget plugin manager (service ID: plugin.manager.field.widget).

E.g. to get all the IDs in your entity class (once the service is injected):

$widget_types = $this->fieldWidgetPluginManager->getDefinitions();
$plugin_ids = array_keys($widget_types);

Same thing in procedural code in case someone wants it:

$widget_types = \Drupal::service('plugin.manager.field.widget')->getDefinitions();
$plugin_ids = array_keys($widget_types);

If your current context allows you to inject the widget plugin manager service rather than get it from \Drupal, all the better.