Scala Play form validation: different forms for on

Question

I'm looking for a way to use two different forms for one case class. I was trying to do that with additional constructor, but failed with that. Look at the code snippet:

case class LoginDetails(password: String, field3: Option[Int], field4: String)

case class User(username: String, loginDetails: LoginDetails) {
   def this(username: String, password: String, field3: Option[Int], field4: String) = this(username, LoginDetails(password, field3, field4))
// some logic inside
    }

val loginDetailsForm = Form(
 mapping(
   "password" -> text,
   "field3" -> optional(number),
   "field4" -> text
 )(LoginDetails.apply)(LoginDetails.unapply))

val oldForm = Form(
 mapping(
   "username" -> email,
   "password" -> text,
   "field3" -> optional(number),
   "field4" -> text
 )(User.apply)(User.unapply))

val newForm = Form(
     mapping(
       "username" -> email,
       "loginDetails" -> loginDetailsForm.mapping
     )(User.apply)(User.unapply))

What I'm trying to do is to support two API's (new and old one), but if I will have two copies of the same case class, I will have to make code logic duplicates in many many places in the rest of the code. If there is a way to do that?

Of course given code doesn't work and is used like an example.

Thanks!

Answer 1

You could try to add methods applyOld and unapplyOld to companion object like this:

case class User(username: String, loginDetails: LoginDetails)
object User {
  def applyOld(username: String, password: String, field3: Option[Int], field4: String) = new User(username, LoginDetails(password, field3, field4))
  def unapplyOld(u: User): Option[(String, String, Option[Int], String)] =
    Some((u.username, u.loginDetails.password,  u.loginDetails.field3,  u.loginDetails.field4))
}

You just need methods (String, String, Option[Int], String) => User and User => Option[(String, String, Option[Int], String)], you could place them anywhere you like. For instance you could create object UserOld with methods apply and unapply.

Usage:

val oldForm = Form(
 mapping(
   "username" -> email,
   "password" -> text,
   "field3" -> optional(number),
   "field4" -> text
 )(User.applyOld)(User.unapplyOld))

val newForm = Form(
     mapping(
       "username" -> email,
       "loginDetails" -> loginDetailsForm.mapping
     )(User.apply)(User.unapply))

Answer 2

You can do the apply/unapply directly where the form is defined instead. Then you don't have to add any new constructors to the case class.

val oldForm = Form(
  mapping(
    "username" -> email,
    "password" -> text,
    "field3" -> optional(number),
    "field4" -> text
  )(
    (username, password, field3, field4) =>
      User(username, LoginDetails(password, field3, field4))
  )(
    (user: User) =>
      Option(user.username, user.loginDetails.password, user.loginDetails.field3, user.loginDetails.field4)
  )
)

val newForm = Form(
  mapping(
    "username" -> email,
    "loginDetails" -> loginDetailsForm.mapping
  )(User.apply)(User.unapply))