[Solved]-compare case class fields with sub fields of another case class in scala-scala

That would be a very easy task to achieve if it would be an easy way to convert case class to map. Unfortunately, case classes don't offer that functionality out-of-box yet in Scala 2.12 (as Mario have mentioned it will be easy to achieve in Scala 2.13).

There's a library called shapeless, that offers some generic programming utilities. For example, we could write an extension function toMap using Record and ToMap from shapeless:

object Mappable {
  implicit class RichCaseClass[X](val x: X) extends AnyVal {
    import shapeless._
    import ops.record._

    def toMap[L <: HList](
        implicit gen: LabelledGeneric.Aux[X, L],
        toMap: ToMap[L]
    ): Map[String, Any] =
      toMap(gen.to(x)).map{
        case (k: Symbol, v) => k.name -> v
      }
    }
}

Then we could use it for findDiff:

def findDiff(profile: Profile): Seq[String] = {
  import Mappable._

  profile match {
    case Profile(_, _, bankInfo, Some(userUpdatedFields)) =>
      val bankInfoMap = bankInfo.toMap
      userUpdatedFields.toMap.toList.flatMap{
        case (k, v) if bankInfoMap.get(k).exists(_ != v) => Some(k)
        case _ => None
      }
    case _ => Seq()
  }
}

Each case class extends Product interface so we could use it to convert case classes into sets of (field, value) elements. Then we can use set operations to find the difference. For example,

  def findDiff(profile: Profile): Seq[String] = {
    val userUpdatedFields = profile.userUpdatedFields.get
    val bankInfoData = profile.bankInfoData

    val updatedFieldsMap = userUpdatedFields.productElementNames.zip(userUpdatedFields.productIterator).toMap
    val bankInfoDataMap = bankInfoData.productElementNames.zip(bankInfoData.productIterator).toMap
    val bankInfoDataSubsetMap = bankInfoDataMap.view.filterKeys(userUpdatedFieldsMap.keys.toList.contains)
    (bankInfoDataSubsetMap.toSet diff updatedFieldsMap.toSet).toList.map { case (field, value) => field }
  }

Now findDiff(profile) should output List(phoneNumber, contactPerson). Note we are using productElementNames from Scala 2.13 to get the filed names which we then zip with corresponding values

userUpdatedFields.productElementNames.zip(userUpdatedFields.productIterator)

Also we rely on filterKeys and diff.

A simple improvement would be to introduce a trait

trait Fields {
  val contactPerson: String
  val phoneNumber: Int
  val accountType: AccountType

  def findDiff(that: Fields): Seq[String] = Seq(
    Some(contactPerson).filter(_ != that.contactPerson).map(_ => "contactPerson"),
    Some(phoneNumber).filter(_ != that.phoneNumber).map(_ => "phoneNumber"),
    Some(accountType).filter(_ != that.accountType).map(_ => "accountType")
  ).flatten
}

case class BankInfoData(accountNumber: Int,
                          bankAddress: String,
                          bankNumber: Int,
                          contactPerson: String,
                          phoneNumber: Int,
                          accountType: String) extends Fields

case class UserUpdatedFields(contactPerson: String,
                           phoneNumber: Int,
                           accountType: AccountType) extends Fields

so it was possible to call

BankInfoData(...). findDiff(UserUpdatedFields(...))

If you want to further-improve and avoid naming all the fields multiple times, for example shapeless could be used to do it compile time. Not exactly the same but something like this to get started. Or use reflection to do it runtime like this answer.