Accessing Scala Case Class parameters in method

Question

I am working on a code where I need to access the fields of a case class based on field name in a method. Explaining in the below code

Case Class Department(
            projectId: String,
            name: Option[String],
            id1: Option[String],
            id2: Option[String],
            id3: Option[String],
            age: Option[Int]
){

def logicOnId(): Boolean = {
  ???
  }
}

I want to write the same logic on all the three ids. I can write it as follows:

def logicOnId1(): Boolean = {
  someLogic(this.id1)
  }

def logicOnId2(): Boolean = {
  someLogic(this.id2)
  }

def logicOnId3(): Boolean = {
  someLogic(this.id3)
  }

But this is not an ideal way since it is the same logic on different columns. So, I want the process/way to write a method so that it can be used on multiple fields like

def logicOnId(input: String): Boolean = {
  someLogic(input)
  }

where this input is id1 or id2 or id3 as a String.

You can use reflection (runtime would be fine in your case), but it's not something encouraged. — AminMal
– AminMal, Commented Apr 18, 2022 at 13:10
Can you please provide the steps or any article for achieving this using reflection ?? — Sarath Chandra Vema
– Sarath Chandra Vema, Commented Apr 18, 2022 at 13:13
1. Runtime reflection is not recommended. 2. Having business logic on case class is not recommended. — cchantep
– cchantep, Commented Apr 18, 2022 at 15:01

Luis Miguel Mejía Suárez · Accepted Answer · 2022-04-18 13:50:19Z

1

No need to go down the route of runtime reflection, just use good type modeling:

final case class Department(
    projectId: String,
    name: Option[String],
    id1: Option[String],
    id2: Option[String],
    id3: Option[String],
    age: Option[Int]
) {
  private def someLogic(input: Option[String]): Boolean =
    ???

  def logicOnId(id: ID): Boolean =
    id match {
      case ID.ID1 =>
        someLogic(this.id1)

      case ID.ID2 =>
        someLogic(this.id2)

      case ID.ID2 =>
        someLogic(this.id3)
    }
}

sealed trait ID
object ID {
  final case object ID1 extends ID
  final case object ID2 extends ID
  final case object ID3 extends ID
}

answered Apr 18, 2022 at 13:50

Luis Miguel Mejía Suárez

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1 Comment

Gaël J Over a year ago

I would use nameOf library to avoid the sealed trait in this case. Not sure it works inside the case class itself though.

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