BaseFieldDefinition change DB column type In a content entity definition, I've got the following:

public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
  $fields = parent::baseFieldDefinitions($entity_type);

  $fields['frames'] = BaseFieldDefinition::create('string')
    -&gt;setLabel(t('Frames'))
  -&gt;setDescription('A serialized representation of the given frames');

  return $fields;
}


This is creating the column type in the database as varchar, with a maxlength of 255. I need the column to be type text, as the length will be unknown, and often more than 255. Does anybody know how to create a BaseFieldDefinition that becomes type 'text' in the database when the content entity is enabled?
You can use BaseFieldDefinition::create('string_long') to get a LONGTEXT type field without the extra__format column.