Question

I am having trouble with the Play! framework’s mapping function. I have suspicion that it may not be able to support the amount of parameters I am passing in as it worked when I limited to just one mapping, but did not find much in the documentation: http://www.playframework.org/documentation/api/2.0.2/scala/index.html#play.api.data.Form

Here is the form:

val paymentForm: Form[PaymentValues] = Form(
// Define a mapping that will handle User values
mapping(
  "message" -> text, 
  "x_card_num" -> text,
  "x_exp_date" -> text,
  "exp_year" -> text,
  "exp_month" -> text,
  "x_card_code" -> text,
  "x_first_name" -> text,
  "x_last_name" -> text,
  "x_address" -> text,
  "x_city" -> text,
  "x_state" -> text,
  "x_zip" -> text,
  "save_account" -> text,
  "product_array" -> text,
  "x_amount" -> text,
  "products_json" -> text,
  "auth_net_customer_profile_id" -> text,
  "auth_net_payment_profile_id" -> text,
  "customer_id" -> text,
  "saved_payments_object" -> text )(PaymentValues.apply)(PaymentValues.unapply))

Any suggestions on breaking up the mapping in some way? Thanks in advance.

This is the error:

! Internal server error, for request [GET /] ->

sbt.PlayExceptions$CompilationException: Compilation error [Overloaded method value [mapping] cannot be applied to  ((java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]), (java.lang.String, play.api.data.Mapping[String]))]
at sbt.PlayReloader$$anon$2$$anonfun$reload$3$$anonfun$2$$anonfun$apply$11$$anonfun$apply$12.apply(PlayReloader.scala:224) ~[na:na]
at sbt.PlayReloader$$anon$2$$anonfun$reload$3$$anonfun$2$$anonfun$apply$11$$anonfun$apply$12.apply(PlayReloader.scala:224) ~[na:na]
at scala.Option.map(Option.scala:133) ~[scala-library.jar:0.11.2]
at sbt.PlayReloader$$anon$2$$anonfun$reload$3$$anonfun$2$$anonfun$apply$11.apply(PlayReloader.scala:224) ~[na:na]
at sbt.PlayReloader$$anon$2$$anonfun$reload$3$$anonfun$2$$anonfun$apply$11.apply(PlayReloader.scala:221) ~[na:na]
at scala.Option.map(Option.scala:133) ~[scala-library.jar:0.11.2]

Here is PaymentValues:

package models
// definition of PaymentValues
case class PaymentValues(
    message: String,
    x_card_num: String,
    x_exp_date: String,
    exp_year: String,
    exp_month: String,
    x_card_code: String,
    x_first_name: String,
    x_last_name: String,
    x_address: String,
    x_city: String,
    x_state: String,
    x_zip: String,
    save_account: String,
    product_array: String,
    x_amount: String,
    products_json: String,
    auth_net_customer_profile_id: String,
    auth_net_payment_profile_id: String,
    customer_id: String,
    saved_payments_object: String)

Answer 1

Looking deeper and deeper in the data API, the limitation comes both from Scala and Play.

Actually, internally, Play will use a case class ObjectMapping to represent a mapping and to define the data binding.
This ObjectMapping case class will take the target’s apply and unapply methods, the domain object (for unapply) and all the 20 parameters as constructor arguments. Count: 23 arguments.

Scala has a limit at 22 (see here) for such Product Abstract Types (tuples, functions, case classes, …).

That’s why a mapping for 20 parameters is not provided by Play… (actually it stops at 18 as said in the great comments to this post)

EDIT

If you don’t believe me… try this ^^

import play.api.data._ 
import validation._
import format._

def mapping[R, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20](a1: (String, Mapping[A1]), a2: (String, Mapping[A2]), a3: (String, Mapping[A3]), a4: (String, Mapping[A4]), a5: (String, Mapping[A5]), a6: (String, Mapping[A6]), a7: (String, Mapping[A7]), a8: (String, Mapping[A8]), a9: (String, Mapping[A9]), a10: (String, Mapping[A10]), a11: (String, Mapping[A11]), a12: (String, Mapping[A12]), a13: (String, Mapping[A13]), a14: (String, Mapping[A14]), a15: (String, Mapping[A15]), a16: (String, Mapping[A16]), a17: (String, Mapping[A17]), a18: (String, Mapping[A18]), a19: (String, Mapping[A19]), a20: (String, Mapping[A20]))(apply: Function18[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, R])(unapply: Function1[R, Option[(A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20)]]): Mapping[R] = {
  ObjectMapping20(apply, unapply, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
}


case class ObjectMapping20[R, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20](apply: Function20[A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20, R], unapply: Function1[R, Option[(A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20)]], f1: (String, Mapping[A1]), f2: (String, Mapping[A2]), f3: (String, Mapping[A3]), f4: (String, Mapping[A4]), f5: (String, Mapping[A5]), f6: (String, Mapping[A6]), f7: (String, Mapping[A7]), f8: (String, Mapping[A8]), f9: (String, Mapping[A9]), f10: (String, Mapping[A10]), f11: (String, Mapping[A11]), f12: (String, Mapping[A12]), f13: (String, Mapping[A13]), f14: (String, Mapping[A14]), f15: (String, Mapping[A15]), f16: (String, Mapping[A16]), f17: (String, Mapping[A17]), f18: (String, Mapping[A18]), f19: (String, Mapping[A19]), f20: (String, Mapping[A20]), val key: String = "", val constraints: Seq[Constraint[R]] = Nil) extends Mapping[R] with ObjectMapping {

  val field1 = f1._2.withPrefix(f1._1).withPrefix(key)

  val field2 = f2._2.withPrefix(f2._1).withPrefix(key)

  val field3 = f3._2.withPrefix(f3._1).withPrefix(key)

  val field4 = f4._2.withPrefix(f4._1).withPrefix(key)

  val field5 = f5._2.withPrefix(f5._1).withPrefix(key)

  val field6 = f6._2.withPrefix(f6._1).withPrefix(key)

  val field7 = f7._2.withPrefix(f7._1).withPrefix(key)

  val field8 = f8._2.withPrefix(f8._1).withPrefix(key)

  val field9 = f9._2.withPrefix(f9._1).withPrefix(key)

  val field10 = f10._2.withPrefix(f10._1).withPrefix(key)

  val field11 = f11._2.withPrefix(f11._1).withPrefix(key)

  val field12 = f12._2.withPrefix(f12._1).withPrefix(key)

  val field13 = f13._2.withPrefix(f13._1).withPrefix(key)

  val field14 = f14._2.withPrefix(f14._1).withPrefix(key)

  val field15 = f15._2.withPrefix(f15._1).withPrefix(key)

  val field16 = f16._2.withPrefix(f16._1).withPrefix(key)

  val field17 = f17._2.withPrefix(f17._1).withPrefix(key)

  val field18 = f18._2.withPrefix(f18._1).withPrefix(key)

  val field19 = f19._2.withPrefix(f19._1).withPrefix(key)

  val field20 = f20._2.withPrefix(f20._1).withPrefix(key)

  def bind(data: Map[String, String]): Either[Seq[FormError], R] = {
    merge(field1.bind(data), field2.bind(data), field3.bind(data), field4.bind(data), field5.bind(data), field6.bind(data), field7.bind(data), field8.bind(data), field9.bind(data), field10.bind(data), field11.bind(data), field12.bind(data), field13.bind(data), field14.bind(data), field15.bind(data), field16.bind(data), field17.bind(data), field18.bind(data), field19.bind(data), field20.bind(data)) match {
      case Left(errors) => Left(errors)
      case Right(values) => {
        applyConstraints(apply(

          values(0).asInstanceOf[A1],
          values(1).asInstanceOf[A2],
          values(2).asInstanceOf[A3],
          values(3).asInstanceOf[A4],
          values(4).asInstanceOf[A5],
          values(5).asInstanceOf[A6],
          values(6).asInstanceOf[A7],
          values(7).asInstanceOf[A8],
          values(8).asInstanceOf[A9],
          values(9).asInstanceOf[A10],
          values(10).asInstanceOf[A11],
          values(11).asInstanceOf[A12],
          values(12).asInstanceOf[A13],
          values(13).asInstanceOf[A14],
          values(14).asInstanceOf[A15],
          values(15).asInstanceOf[A16],
          values(16).asInstanceOf[A17],
          values(17).asInstanceOf[A18],
          values(18).asInstanceOf[A19],
          values(19).asInstanceOf[A20]))
      }
    }
  }

  def unbind(value: R): (Map[String, String], Seq[FormError]) = {
    unapply(value).map { fields =>
      val (v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13, v14, v15, v16, v17, v18, v19, v20) = fields
      val a1 = field1.unbind(v1)
      val a2 = field2.unbind(v2)
      val a3 = field3.unbind(v3)
      val a4 = field4.unbind(v4)
      val a5 = field5.unbind(v5)
      val a6 = field6.unbind(v6)
      val a7 = field7.unbind(v7)
      val a8 = field8.unbind(v8)
      val a9 = field9.unbind(v9)
      val a10 = field10.unbind(v10)
      val a11 = field11.unbind(v11)
      val a12 = field12.unbind(v12)
      val a13 = field13.unbind(v13)
      val a14 = field14.unbind(v14)
      val a15 = field15.unbind(v15)
      val a16 = field16.unbind(v16)
      val a17 = field17.unbind(v17)
      val a18 = field18.unbind(v18)
      val a19 = field19.unbind(v19)
      val a20 = field20.unbind(v20)

      (a1._1 ++ a2._1 ++ a3._1 ++ a4._1 ++ a5._1 ++ a6._1 ++ a7._1 ++ a8._1 ++ a9._1 ++ a10._1 ++ a11._1 ++ a12._1 ++ a13._1 ++ a14._1 ++ a15._1 ++ a16._1 ++ a17._1 ++ a18._1 ++ a19._1 ++ a20._1) ->
        (a1._2 ++ a2._2 ++ a3._2 ++ a4._2 ++ a5._2 ++ a6._2 ++ a7._2 ++ a8._2 ++ a9._2 ++ a10._2 ++ a11._2 ++ a12._2 ++ a13._2 ++ a14._2 ++ a15._2 ++ a16._2 ++ a17._2 ++ a18._2 ++ a19._2 ++ a20._2)
    }.getOrElse(Map.empty -> Seq(FormError(key, "unbind.failed")))
  }

  def withPrefix(prefix: String): ObjectMapping20[R, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20] = addPrefix(prefix).map(newKey => this.copy(key = newKey)).getOrElse(this)

  def verifying(addConstraints: Constraint[R]*): ObjectMapping20[R, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18, A19, A20] = {
    this.copy(constraints = constraints ++ addConstraints.toSeq)
  }

  val mappings = Seq(this) ++ field1.mappings ++ field2.mappings ++ field3.mappings ++ field4.mappings ++ field5.mappings ++ field6.mappings ++ field7.mappings ++ field8.mappings ++ field9.mappings ++ field10.mappings ++ field11.mappings ++ field12.mappings ++ field13.mappings ++ field14.mappings ++ field15.mappings ++ field16.mappings ++ field17.mappings ++ field18.mappings ++ field19.mappings ++ field20.mappings

}