Akka-HTTP JSON serialization - scala

Question

How does one control the deserialization for spray-json? For example, I have a class defined as:
case class A (Name:String, Value:String)
And I would like to deserialize the following JSON into a List of A objects:
{
"one": "1",
"two": "2"
}
and it should become:
List(A("one", "1"), A("two", "2"))
The problem is that the default JSON representation of that List is this one, which I do not want:
[
{ "Name": "one", "Value": "1" },
{ "Name": "two", "Value": "2" }
]
How can I accomplish this?

Answer 1

You can write your own custom deserializer for the structure you are looking for:
case class A(Name:String, Value:String)
implicit object ListAFormat extends RootJsonReader[List[A]] {
override def read(json: JsValue): List[A] = {
json.asJsObject.fields.toList.collect {
case (k, JsString(v)) => A(k, v)
}
}
}
import spray.json._
def main(args: Array[String]): Unit = {
val json =
"""
|{
| "one": "1",
| "two": "2"
|}
""".stripMargin
val result = json.parseJson.convertTo[List[A]]
println(result)
}
Prints:
List(A(one,1), A(two,2))