Built in parsing of a string to a Scala case object?

Is there any way to automatically parse a case object from a string, in Scala? Using some built in / automatically generated Scala function?

For example, I have these case objects: (please note that there's a sealed parent class)

abstract sealed class FlagReason

case object Spam extends FlagReason
case object Illegal extends FlagReason
case object CopyrightViolation extends FlagReason
case object Other extends FlagReason

and I开发者_JS百科'm wondering if there's some automatically generated function that works like:

FlagReason.fromString(value: String): FlagReason

where FlagReason("Spam") would return the Spam case object.

If there were, then I need not write my own -- which I've done:

object FlagReason {
  def fromString(value: String): FlagReason = value match {
    case "Spam" => Spam
    case "Illegal" => Illegal
    case "CopyrightViolation" => CopyrightViolation
    case "Other" => Other
  }
}

Background: I'm converting my case objects to strings that I use as radio button values in a html form. I'm converting the selected value back to a case object, when I handle the submitted form.

Related info: This is actually possible with Java enums, see e.g. this StackOverflow question: Lookup enum by string value

((I don't think I'm looking for Scala's Parser Combinators. I suppose that were I to use them I'd still need to define the parsing rules myself, rather than having built in "automatic" string to case object conversion))

---

No, no such method is automatically generated. You will have to write your own fromString method. Note that you can write it more compactly as follows:

object FlagReason {
  def fromString(value: String): Option[FlagReason] = {
    Vector(Spam, Illegal, CopyRightViolation, Other).find(_.toString == value)
  }
}

Alternatively you may consider using scala.Enumeration which does provide this facility.

object FlagReason extends Enumeration {
  val Spam, Illegal, CopyRightViolation, Other = Value
}

Then you can obtain the particular enum value with FlagReason withName "<name>", or safely as an Option with Try(FlagReason withName "<name>").toOption.

---

As missingfaktor points out, FlagReason withName "<name>" should do what you need. But if <name> is not a valid name, it will throw an exception. So, a slightly safer way to handle this when you are not sure if the name is valid is to use Option[FlagReason]:

scala> def parse(name: String) = FlagReason.values.find(_.toString == name)
parse: (name: String)Option[FlagReason.Value]

scala> parse("Spam")
res0: Option[FlagReason.Value] = Some(Spam)

scala> parse("NonExisting")
res1: Option[FlagReason.Value] = None