CODEWITHSUNDEEP
scalapattern-matching
goralph
goralph

Reputation: 1086

Pattern match for the existence of an attribute present in a case class

Here is an example case class:

case class Person( firstName: Either[Unit, String], middleName: Either[Unit, Option[String], lastName: Either[Unit,String])

Any time I get an instance of this case class with a middleName it is invalid and I want to do something, all other cases are ok.

EDIT

To clarify. I need to guard against using an instance of this case class in a certain method if it was constructed with a middleName. So I would want to do something like this:

person match {
    case Person(_,m,_) => halt()
    case _ => continue()
}

I'm just having a hard time thinking about the types involved here.

Upvotes: 0

Views: 217

Answers (1)

vptheron
vptheron

Reputation: 7466

Your pattern matching does not test the actual value of middleName, it simply assigns it to m. All Person instances are gonna match this first case.

If you want to call halt if middleName is a Right for example you should write:

person match {
  case Person(_, Right(_), _) => halt() 
  case _ => continue()
}

If you want to dive into the value of Right to see if it's a Some:

person match {
  case Person(_, Right(Some(_)), _) => halt() 
  case _ => continue()
}

Upvotes: 3

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