forとパターンマッチ あとはcollect

ForCollect.scala

case class Data(opt: Option[String])
val tList = List(Data(None), Data(Some("hoge")), Data(None), Data(Some("fuga")), Data(Some("piyo")))


for(Data(Some(str)) <- tList) yield str

tList.collect {
  case Data(Some(str)) => str
}


// Dataの中に複数のOptionがある場合

case class Data2(opt: Option[String]*)
val tList2 = List(Data2(None, Some("foo")), Data2(Some("hoge"), Some("bar")), Data2(None), Data2(Some("fuga")), Data2(Some("piyo")))

tList2.flatMap {
  case Data2(seq @ _*) => seq.flatten
}

repl

scala> for(Data(Some(str)) <- tList) yield str
res26: List[String] = List(hoge, fuga, piyo)

scala> tList.collect {
     |   case Data(Some(str)) => str
     | }
res27: List[String] = List(hoge, fuga, piyo)

scala> tList2.flatMap {
     |   case Data2(seq @ _*) => seq.flatten
     | }
res28: List[String] = List(foo, hoge, bar, fuga, piyo)