How to turn json to case class when case class has only one field

As Julien answered, you can read single field case classes using this:

case class Person(name: String)

val personReads: Reads[Person] = 
  (__ \ "name").read[String].map { name => Person(name) }

Just a complement, if you want to write:

val personWrites: Writes[Person] = 
  (__ \ "name").write[String].contramap { (person: Person) => person.name }

Or format (read and write):

val personFormat: Format[Person] = 
  (__ \ "name").format[String].inmap(name => Person(name), (person: Person) => person.name)

For write and format you have to import this:

import play.api.libs.functional.syntax._