reflection - scala case class conversation for DTO(shapeless) - Stack Overflow

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I want convert case class UserDTO to case class User I find solution in shapeless case class conversion

class SameFieldConverter[T] {
def apply[S, SR <: HList, TR <: HList, MR <: HList, IR <: HList](s: S)(implicit
  genS: LabelledGeneric.Aux[S, SR],
  genT: LabelledGeneric.Aux[T, TR],
  merger: Merger.Aux[SR, HNil, MR],
  intersection: Intersection.Aux[MR, TR, IR],
  align: Align[IR, TR]) = genT.from(intersection(merger(genS.to(s), HNil)))

but i have problem with diffirent field, example in UserDTO i have field name, surname, but in User i have fullName.

  case class UserDTO(name:String, surname:String, age:Int){
    def toDomain:User = User(name + surname, age)
  }
  case class User(fullName:String, age:Int)

Also I have problem with diffirent field names exaples name -> last name

case class UserDTO(name:String, surname:String, age:Int)
case class User(firstName:String, surname:String, age:Int)

I think about solution like in a quill alias("name", _.surname), but i have small brain. I was also thinking of looking into the use of scala reflection API

I want convert case class UserDTO to case class User I find solution in shapeless case class conversion

class SameFieldConverter[T] {
def apply[S, SR <: HList, TR <: HList, MR <: HList, IR <: HList](s: S)(implicit
  genS: LabelledGeneric.Aux[S, SR],
  genT: LabelledGeneric.Aux[T, TR],
  merger: Merger.Aux[SR, HNil, MR],
  intersection: Intersection.Aux[MR, TR, IR],
  align: Align[IR, TR]) = genT.from(intersection(merger(genS.to(s), HNil)))

but i have problem with diffirent field, example in UserDTO i have field name, surname, but in User i have fullName.

  case class UserDTO(name:String, surname:String, age:Int){
    def toDomain:User = User(name + surname, age)
  }
  case class User(fullName:String, age:Int)

Also I have problem with diffirent field names exaples name -> last name

case class UserDTO(name:String, surname:String, age:Int)
case class User(firstName:String, surname:String, age:Int)

I think about solution like in a quill alias("name", _.surname), but i have small brain. I was also thinking of looking into the use of scala reflection API

• scala
• reflection
• shapeless

Share Improve this question Follow edited Feb 13 at 1:05 Dmytro Mitin 51.8k33 gold badges3232 silver badges7373 bronze badges asked Feb 12 at 20:47 LindenesLindenes 2544 bronze badges 1

• 2 So what is your question? There are a few mapping libraries made for that (higher level than shapeless), like chimney. – Gaël J Commented Feb 12 at 21:13

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1 Answer 1

Sorted by: Reset to default 4

If you just want to convert from a case class to another case class where both have same or similar fields, I think shapeless is an overkill. I would choose chimney for something like that. The code should look like

• build.sbt

libraryDependencies += "io.scalaland" %% "chimney" % "1.7.3"

• Transformer.scala

import io.scalaland.chimney.dsl._

case class UserDTO(name:String, surname:String, age:Int)
case class User(firstName:String, surname:String, age:Int)

class Transformer {
  def fromUserDtoToUser(userDTO: UserDTO): User = {
    userDTO
      .into[User]
      .withFieldComputed(_.firstName, _.name) // here is the mapping between fields with different names
      .transform
  }
}

and a dummy main method should look like

• Main.scala

object Main {
  def main(args: Array[String]): Unit = {
    val transformer = new Transformer
    val userDTO = UserDTO("john", "doe", 30)
    val user = transformer.fromUserDtoToUser(userDTO)
    println(userDTO)
    println(user)
  }
}

The output will be

UserDTO(     name = john, surname = doe, age = 30)
User(   firstName = john, surname = doe, age = 30)

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