how to apply Form validators on object

Question

I have an API in Scala. When I want to create a new User, i need validators on some fields (UserName, FirstName, LastName). I can't find a solution to apply the Form on my case class User. I thought using (User.apply) this will override automatically my User class, but this isn't happening.

User.scala

 case class User(
              id: Int = 0,
              userName: String,
              firstName: String,
              lastName: String
            )

object User {
  import play.api.libs.json._

  implicit val jsonWrites = Json.writes[User]

  implicit val userReads = Json.reads[User]

  def tupled = (User.apply _).tupled
}

// Form validator for post requests
object UserForm {
  val form: Form[User] = Form(
    mapping(
      "id" -> number,
      "userName" -> text(minLength = 5),
      "firstName" -> text(minLength = 5),
      "lastName" -> nonEmptyText
    )(User.apply)(User.unapply)
  )
}

UsersController.scala

def create = Action(parse.json) { implicit request => {
    val userFromJson = Json.fromJson[User](request.body)
    userFromJson match {
      case JsSuccess(user: User, path: JsPath) => {
        var createdUser = Await.result(usersRepository.create(user), Duration.Inf)
        Ok(Json.toJson(createdUser))
      }
      case error @ JsError(_) => {
        println(error)
        InternalServerError(Json.toJson("Can not create user"))
      }
      }
    }
  }

UsersRepository.scala

    def create(user: User): Future[User] = {
      val insertQuery = dbUsers returning dbUsers.map(_.id) into ((x, id) => x.copy(id = id))
      val query = insertQuery += user
      db.run(query)
    }

(UsersRepository doesn't matter so much in this problem)

So, when I read the json, I think there need to apply the form validators

val userFromJson = Json.fromJson[User](request.body)

but nothing happening. Another problem is if I send from client a null parameter, will get an error, can not read and create an User.

For example :

"firstName": "" - empty userName will pass

"firstName": null - will fail

This depends on how is configured the User class in client (Angular), with the field null or empty in constructor. I prefer to set it null, even if is a string, if is not a required field (better NULL value in database, than an empty cell)

Answer 1

Find a solution, my Form need to be part of object User, and not to be another object.

  object User {
  import play.api.libs.json._

  implicit val jsonWrites = Json.writes[User]    
  implicit val userReads = Json.reads[User]

  val form: Form[User] = Form(
    mapping(
      "id" -> number,
      "userName" -> text(minLength = 2),
      "firstName" -> text(minLength = 4),
      "lastName" -> nonEmptyText
    )(User.apply)(User.unapply)
  )

  def tupled = (User.apply _).tupled
}

and the method in Controller became :

def create = Action(parse.json) { implicit request => {
    User.form.bindFromRequest.fold(
      formWithErrors => BadRequest(Json.toJson("Some form fields are not validated.")),
      success => {
        val userFromJson = Json.fromJson[User](request.body)
        userFromJson match {
          case JsSuccess(user: User, path: JsPath) => {
            val createdUser = Await.result(usersRepository.create(user), Duration.Inf)
            Ok(Json.toJson(createdUser))
          }
          case error@JsError(_) => {
            println(error)
            InternalServerError(Json.toJson("Can not create user"))
          }
        }
      }
    )
   }
  }

I know, I need to format my code ... using IntelliJ is so annoying after Visual Studio :(