Repository

FrontendUserRepository provides the following functionality:

findByUsername

The method is used to find frontend user by username and page Uid.

/**
 * Find frontend user by username
 *
 * @param string $username
 * @param int $pid
 * @return FrontendUser|null
 */
public function findByUsername(string $username, int $pid = 0): ?FrontendUser
{
    $query = $this->createQuery();

    if ($pid) {
        $settings = $query->getQuerySettings();
        $storagePageIds = $settings->getStoragePageIds();
        $storagePageIds[] = $pid;
        $settings->setStoragePageIds(array_unique($storagePageIds));
    }

    $constraint = $query->equals('username', $username);
    $query->matching($constraint);

    $result = $query->execute();

    return $result->getFirst();
}