Scala write collection of objects to HttpResponse - scala

Question

I'm scala beginner and for now I'm trying to build a basic play/slick app (sort of user database).
It seems I've been able to build up all the stuff but data transferring to the front-end.
Here is what I have:
UserDAO.scala
class UserDao #Inject()(protected val dbConfigProvider: DatabaseConfigProvider) extends BaseDao {
import driver.api._
def entities = TableQuery[UsersTable]
def all(): Future[Seq[User]] = {
db.run(entities.result)
}
class UsersTable(tag: Tag) extends BaseTable(tag, "USER") {
def email = column[String]("email")
def password = column[String]("password")
def * = (id, email, password) <> (User.tupled, User.unapply)
}
}
Application.scala
Application #Inject()(userDAO: UserDao) extends Controller {
def users = Action.async {
val userList = userDAO.all()
userList
.map { list => Ok(list.map(elem => Json.toJson(elem : UserDto))) }
.recover { case _ => InternalServerError }
}
}
UserDTO.scala
case class UserDto(id: Long, login: String)
object UserDto {
implicit val userWriter = Json.writes[UserDto]
implicit def from(user: User): UserDto = UserDto(user.id, user.login)
}
What I don't understand is why compiler complains about .map { list => Ok(list.map(elem => Json.toJson(elem : UserDto))) } in Application.scala. It seems that I provided everything required for conversion to json. Could please, anybody, show what I'm doing wrong?

Answer 1

Replace Ok(list.map(elem => Json.toJson(elem : UserDto))) with Json.toJson(list: Seq[UserDto])
Application #Inject()(userDAO: UserDao) extends Controller {
def users = Action.async {
val userList = userDAO.all()
userList
.map { list => Ok(Json.toJson(list: Seq[UserDto])) }
.recover { case _ => InternalServerError }
}
}