Question

I’m using an api that I can’t change that returns a 2-element map where one key is always present but the other key/value pair is dynamic, and I’m trying to unpack them into a case class. The code below works, but is really ugly:

case class Foo(name: String, key: String, value: String)

def fooFromMap(item: Map[String, String]): Option[Foo] = {
  var name: String = null
  var key: String = null
  var value: String = null
  item.foreach { 
    case ("name", v) => name = v
    case (k, v) => key = k; value = v
  }
  if(name != null && key != null && value != null) Some(Foo(name, key, value))
  else None
}

Is there a nicer way to do this?

Answer 1

The following is equivalent, and more idiomatic:

def fooFromMap(item: Map[String, String]): Option[Foo] = for {
  name   <- item get "name"
  (k, v) <- (item - "name").headOption
} yield Foo(name, k, v)

If either item get "name" or (item - "name").headOption comes up empty, the result will be empty—otherwise you get the Foo you want.