Extract Type T from Seq[T]

Question

I have a case class which has got two fields which are a Seq[Objects]. These two objects belong to two different case classes.

  case class Passport(country: String, name: String)
  case class DrivingLicence(code: String, name: String)
  case class Docs(passports : Seq[Passport], driv: Seq[DrivingLicence])

  val pass1 = Passport("UK", "Michael")
  val pass2 = Passport("USA", "Michael")

  val driv1 = DrivingLicence("A2", "Mich")
  val driv2 = DrivingLicence("A4", "Mich")

  val docs = Docs(Seq(pass1,pass2), Seq(driv1,driv2))

I can generate a map with all the attributes and their types like follows:

  val r = currentMirror.reflect(docs)
  val mapType = r.symbol.typeSignature.members.toStream
    .collect{case s : TermSymbol if !s.isMethod => r.reflectField(s)}
    .map(r => r.symbol.name.toString.trim -> r.symbol.typeSignature)
    .toMap
println("Map of Types: "+mapType)

And the output is:

Map of Types: Map(driv -> Seq[DrivingLicence], passports -> Seq[Passport])

But what I would like is to get rid of the Seq part, and obtain the inner type. Something like:

Map of Types: Map(driv -> DrivingLicence, passports -> Passport)

How could I access the inner type of a Seq[_]?

Answer 1

You can get a list of type arguments with typeArgs, but it will return List[Type], so you would need to take the first element with head:

r.symbol.typeSignature.typeArgs.head