List to Json in Playframework Scala

Question

I am new to scala and to the playframework, but so far it is great. I am having trouble figuring out how to turn a list of data into json (or really any complex structure). This isn't a real-world example, but here is what I am trying to do. Get some data from a database.

scala> val result:List[(Long,String)] = DB.withConnection { implicit c => 
    SQL("select * from users").as(
     long("id")~str("uid") map(flatten)*)
  }
 result: List[(Long, String)] = List((3,397a73ee5150429786863db144341bb3), (4,2850760dc9024c16bea6c8c65f409821), (5,636ee2bf758e4f699f27890ac55d7db2))

I would like to be able to then turn that into json and return it. based on this doc, it looks like i need to iterate through and call toJson on the result

http://www.playframework.org/documentation/2.0/ScalaJson

But, In practice i am having trouble doing it. Is this even the correct approach? Is there some scala concept that would make this simple? I see some examples using case classes, but I haven't quite wrapped my head around that concept yet.

I don't really expect this to work but, i guess I am conceptually trying to do something like this

scala> toJson(Map("response" -> result))
<console>:27: error: No Json deserializer found for type     scala.collection.immutable.Map[java.lang.String,List[(Long, String)]]. Try to implement an     implicit Writes or Format for this type.
          toJson(Map("response" -> result))

Thanks

Answer 1

As said, you can write you own implicit Writes to do that but you can also rely on the existing Writes and just retrieve your data as a List[Map[String, Any]] and apply toJson on it:

val simple = {
    get[Pk[Long]]("user.id") ~
    get[Long]("user.uid") map {
        case id~uid => Map("id" -> id.get.toString, "uid" -> uid.toString)
    }
}
val result:List[Map(String,String)] = DB.withConnection { implicit c => 
    SQL("select * from users").as(User.simple *)
}