Getter on nested case class

Question

I would like to get value of a nested case class giving a "path" in this nested case class.

For example, giving:

case class Address(street : String, city : String, postcode : String)
// Nested case class
case class Person(name : String, age : Int, address : Address)

val person = Person("Joe Grey", 37, Address("Southover Street", "Brighton", "BN2 9UA"))

val path = "address_street" // _ is arbitrary separator

I would like getter(path) returns "Southover Street".

I try different things with shapeless' lenses like

val steetLens = lens[Person] >> Witness(Symbol("address")) >> Witness(Symbol("street"))
println(steetLens.get(person))

which return the right thing but I can't use it in a generic way because something like this:

 val steetLens = lens[Person] >> addressField >> streetField

doesn't work..

As far as I understand we can't create Symbol from generic string.

https://stackoverflow.com/questions/49710536/deriving-nested-shapeless-lenses-using-only-a-type — Dmytro Mitin, Oct 26 '18 at 16:29

score 0 · Answer 1 · answered Oct 27 '18 at 07:04

0

Can you use standard composition of lenses?

val address: Lens[Person, Address] = lens[Person].address
val street: Lens[Address, String] = lens[Address].street
val addressStreet: Lens[Person, String] = street compose address
addressStreet.get(person) // Southover Street

answered Oct 27 '18 at 07:04

Dmytro Mitin

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The idea is something like that but I would like to use string to access object in Lens, like: `lens[Person]("address")` or something similar – Thomas Oct 29 '18 at 09:19

Getter on nested case class

1 Answers1