How can I iterate over my Enumeration values that contain a particular value?-CodePudding

I have an enumeration that currently for some reason is not outputting anything when I loop over the values:

 object UserType extends Enumeration {
    type UserType = UTValue

    protected case class UTValue(name: String, roles: Set[String]) extends super.Val {
     // override def toString(): String = name
    }

    val anonymous = UTValue("anonymous", Set.empty)
    val superUser = UTValue("super", Set("member", "admin", "edit", "delete"))
  }

  println(UserType.anonymous)
  println(UserType.superUser)
  println(UserType.values.map(println))

The output is:

anonymous
superUser
anonymous
superUser
TreeSet(())

Why is an empty TreeSet(()) being returned?

My main question: How can I iterate over all the Enumeration values that contain the role "member".

UserType.values.filter(_.roles.contains("member"))

(scala 2.13.x)

CodePudding user response：

You are printing value inside the map and println returns Unit, if you remove println inside the map like println(UserType.values.map(value => value))

 object UserType extends Enumeration {
    type UserType = UTValue

    protected case class UTValue(name: String, roles: Set[String]) extends super.Val {
      // override def toString(): String = name
    }

    val anonymous = UTValue("anonymous", Set.empty)
    val superUser = UTValue("super", Set("member", "admin", "edit", "delete"))
  }

  println(UserType.anonymous)
  println(UserType.superUser)
  println(UserType.values.map(x => x))

And since it is TreeSet it removes duplicate values and keeps only one Unit value (), that is why you are getting TreeSet(())

CodePudding user response：

You need implicit conversion in UserType.

object UserType extends Enumeration {
    type UserType = UTValue

    protected case class UTValue(name: String, roles: Set[String]) extends super.Val {
        // override def toString(): String = name
    }

    val anonymous = UTValue("anonymous", Set.empty)
    val superUser = UTValue("super", Set("member", "admin", "edit", "delete"))

    import scala.language.implicitConversions
    implicit def valueToUTValue(x: Value): UTValue = x.asInstanceOf[UTValue]
}

UserType.values.filter(_.roles.contains("member")).foreach(println)