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scalacopylagom

how to copy a class inside of a state?

Its quite simple if all of the val in the State is basic data type. if we want to copy a specific value inside of it, it would just be

copy(specificValue = newValue)

but how if this specific value, is inside of a class? this is what I have tried but with no avail

copy(specificClass.specificValue = newValue)

should I instead create/copy this class outside, then make it like bellow?

copy(specificClass = newClass)

Solution

  • if you have

    
case class Address(street: String, city: String)
case class User(address: Address, name: String)

val u = User(...)

//to change the city to something else you would do

val another = u.copy(address = u.address.copy(city = "New York")

    This is cumbersome. I recommend using quicklens library which will allow you to write:

    
 import com.softwaremill.quicklens._

 val another = u.modify(_.address.city).setTo("New York")