CODEWITHSUNDEEP
scala
Mojo
Mojo

Reputation: 1202

Pattern Matching on Case Class With Option Fields

I have a case class like this:

case class Foo(a : Option[String], b : Option[String])

and I want to pattern match on it to see if the values are present in the fields or not. What is the best way to do this?

I did the following but it doesn't work because it is thinking I am trying to create an instance of Foo:

val ff = Foo(Some("a"), None)

//psuedo code
ff match {
case Foo(a, b) => do something // all values present
case Foo(None, None) => error

Upvotes: 0

Views: 731

Answers (2)

Brian
Brian

Reputation: 20285

case Foo(a,b) will match any Foo(Option, Option) since you are not matching on an instance of Option. e.g. Some or None.

See Luis's comment above too.

scala> ff match{
     | case Foo(None, None) => "nn"
     | case Foo(None, Some(a)) => "ns"
     | case Foo(Some(a), None) => "sn"
     | case Foo(Some(a), Some(b)) => "ss"
     | }
res4: String = sn

Upvotes: 1

Pritam Kadam
Pritam Kadam

Reputation: 2527

You can do following:


  case class Foo(a: Option[String], b: Option[String])

  val ff = Foo(Some("a"), None)

  //psuedo code
  ff match {
    case Foo(Some(a), Some(b)) => // when both a and b present
    case Foo(Some(a), None)    => // when only a present
    case Foo(None, Some(b))    => // when only b present
    case Foo(None, None)       => // when both a and b are not present
  }

Upvotes: 1

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