Get List of TYPO3 FE_User Group - typo3

Question

How can I get a list with all my frontenduser groups?
I've tried this:
/**
* feUserGroupRepository
*
* #var \TYPO3\CMS\Extbase\Domain\Repository\FrontendUserGroupRepository
* #inject
*/
protected $feUserGroupRepository = NULL;`
and then this:
$usergroups = $this->feUserGroupRepository->findAll();
I got this error: Call to a member function findAll() on a non-object
And I tried this way:
/**
* #var \TYPO3\CMS\Extbase\Domain\Repository\FrontendUserGroupRepository $feUserGroupRepository
*/
$feUserGroupRepository = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\\CMS\\Extbase\\Domain\\Repository\\FrontendUserGroupRepository');
$allUsers = $feUserGroupRepository->findAll();`
dosn't work at all i've got this error message
PHP Catchable fatal error: Argument 1 passed to
TYPO3\CMS\Extbase\Persistence\Repository::__construct() must implement interface
TYPO3\CMS\Extbase\Object\ObjectManagerInterface, none given, called in
C:\xampp\htdocs\typo3\typo3\sysext\core\Classes\Utility\GeneralUtility.php on
line 4431 and
defined in C:\xampp\htdocs\typo3\typo3\sysext\extbase\Classes\Persistence\Repository.php
How can I get a list with all feusergroups?
Rcord Type?

Answer 1

The error indicates that the Dependency Injection didn't work. Please make sure that you flush the System Cache after doing changes that are cached in the Database, which is the case for changes of class names or changes that require dependencies to be rebuilt.
You can flush the system cache in the Install Tool ("Important actions") or directly in the Backend if you are running TYPO3 in Development context. "Flush general caches" does not (!) flush the database-based system caches.
Depending on the TYPO3 version you're running, you will need to set the Record Type of your Frontend Usergroups (column "tx_extbase_type") to FrontendUserGroup.
Using makeInstance for generating an instance of a Repository is discouraged. You should use dependency injection where possible (in this case it is), or, where not possible, the ObjectManager.