Scala generics usage for methods + json4s parsing - scala

Question

I am not sure if this is achievable and I have a very basic understanding of how generics work in scala. But I was wondering if this is possible.
Say I have a method:
case class Person(id:String,name:String)
case class Student(id:String,name:String, class:String)
def convertToJson[A](fileName:String):{
//read file
parse[A]
}
Is it possible to write this generic method which would parse the json based on the type of class I send when I call the convertToJson method?
Something like:
convertToJson[Student](fileName)
convertToJson[Person](fileName)
BTW the above code gives me a :
No Manifest available for A. error.
Using json4s for parsing.
Any help is appreciated.

Answer 1

This will convert a JSON string to a case class
import org.json4s._
import org.json4s.jackson.JsonMethods._
def convertToJson[T](json: String)(implicit fmt: Formats = DefaultFormats, mf: Manifest[T]): T =
Extraction.extract(parse(json))
Once this is defined you can parse appropriate strings to the required type:
case class Person(id: String, name: String)
case class Student(id: String, name: String, `class`: String)
val person = convertToJson[Person]("""{"name":"Jane","id":45}""")
val student = convertToJson[Student]("""{"name":"John","id":63, "class": "101"}""")
Note that this will ignore JSON data that does not match fields in the case class. If a field is optional in the JSON, make it an Option in the case class and you will get None if the field is not there.