CODEWITHSUNDEEP
scalamapspattern-matching
b1399877
b1399877

Reputation: 27

Dynamically add element to map after pattern matching

I have a method as follows:

  protected def extract(implicit params:Params) =
    Map(
  "address" -> params.address,
  "city" -> params.address,
  "region" -> params.region,
)collect {
    case (k, v) if v.isDefined => k -> v.get
  }

I want to substitute value of city such that :

"city" -> if(params.city.contains("York")) "NewYork" else params.city,

How can I achieve this in scala?

Upvotes: 0

Views: 77

Answers (3)

mavarazy
mavarazy

Reputation: 7735

Small correction to Bruce answer

myMap.collect {
   case ("city", Some(city)) if(city.contains("York")) => "NewYork"
   case (k, v) if v.isDefined => k -> v.get
}

Would not result in a Map, but an Iterable

myMap.collect {
   case ("city", Some(city)) if(city.contains("York")) => "city" -> "NewYork"
   case (k, Some(v)) => k -> v
}

Would be better

Upvotes: 0

Bruce Lowe
Bruce Lowe

Reputation: 6193

Stephens approach of just creating the map with the correct value is probably best. If you've got a general map, of what appears to be String to Option[String], and want to substitute the city key if the value contains York, then this will work as well.

 myMap.collect {
    case ("city", Some(city)) if(city.contains("York")) => "NewYork"
    case (k, v) if v.isDefined => k -> v.get
  }

Upvotes: 1

Stephen
Stephen

Reputation: 4296

You could put it in line

def extract(implicit params:Params) = 
    Map(
  "address" -> params.address,
  "city" -> (if(params.city.contains("York")) Some("NewYork") else params.city),
  "region" -> params.region
) collect {
    case (k, v) if v.isDefined => k -> v.get
  }

Im sure there are lots of other way to do it. Not sure what your really after.

Upvotes: 1

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