@startuml
class User {
    protected $userId
    protected $username
    protected $email
    +__construct($id = null, $username = null, $email = null)
    +getUserId()
    +setUserID($userId)
    +getUsername()
    +setUsername($username)
    +getEmail()
    +setEmail($email)
}

class UserMapper {
    protected $adapter
    +__construct(DBAL $dbLayer)
    +save(User $user)
    +findById($id)
    +findAll()
    +mapObject(array $row)
}

User
UserMapper
@enduml