Scala safe way of converting String to Enumeration value

Question

Suppose I have enumeration:

object WeekDay extends Enumeration {   type WeekDay = Value   val Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value } 

I would like to be able to convert String to WeekDay value and this is fine with:

scala> WeekDay.withName("Tue") res10: WeekDay.Value = Tue 

But if I pass some 'unknown' value, I'm getting exception:

scala> WeekDay.withName("Ou") java.util.NoSuchElementException: None.get   at scala.None$.get(Option.scala:322)   at scala.None$.get(Option.scala:320)   at scala.Enumeration.withName(Enumeration.scala:124)   ... 32 elided 

Is there some elegant way of safely convert String to Enumeration value?

Answer 1

You can add a method to the enumeration to return an Option[Value]:

def withNameOpt(s: String): Option[Value] = values.find(_.toString == s) 

Note: the existing withName method actually does precisely this, then calls getOrElse throwing the exception in the "else" case.

Answer 2

Building on top of @Shadowlands 's answer, I added this method to my enum to have a default Unknown value without dealing with options:

def withNameWithDefault(name: String): Value =   values.find(_.toString.toLowerCase() == name.toLowerCase()).getOrElse(Unknown) 

so the enum would look like this:

object WeekDay extends Enumeration {   type WeekDay = Value   val Mon, Tue, Wed, Thu, Fri, Sat, Sun, Unknown = Value    def withNameWithDefault(name: String): Value =      values.find(_.toString.toLowerCase() == name.toLowerCase()).getOrElse(Unknown) }