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

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

@enduml