public function getByUsername($username)
{
$sql = "select user.username as user_username, password, name, surname, email, challangeID, startdatum, einddatum, startgewicht, eindgewicht" . " from user, challanges where user.username = challanges.username and challanges.username = :user";
$dbh = new PDO(DBConfig::$DB_CONNSTRING, DBConfig::$DB_USERNAME, DBConfig::$DB_PASSWORD);
$stmt = $dbh->prepare($sql);
$stmt->execute(array(':user' => $username));
$rij = $stmt->fetch(PDO::FETCH_ASSOC);
$user = User::create($rij["user_username"], $rij["password"], $rij["name"], $rij["surname"], $rij["email"]);
$challenge = Challenge::create($rij["challangeID"], $user, $rij["startdatum"], $rij["einddatum"], $rij["startgewicht"], $rij["eindgewicht"]);
// var_dump($challenge);
$dbh = null;
return $challenge;
}