json to json transform using play 2.3, combining fields - json

Question

I am trying to combine a couple of fields from a json structure into a another json structure using play 2.3. Basically what I want to do is take this:
{
"a": "aaa"
"b": "bbb"
"c":
{
"d": "ddd"
"e": 123456
"f": "ffff"
}
}
and turn it into this:
{
"a": "aaa"
"b": "bbb"
"new": "ddd123456fff
}
I've had a look at a solution here: https://groups.google.com/forum/#!msg/play-framework/6MdDYf1JjEg/z_WG3DcdQIQJ
but the 'and' isn't available and I don't think 'andThen' is the same thing.

Answer 1

You could do the following
scala> import play.api.libs.json._
scala> val json: JsValue = Json.parse("""
{
"a": "aaa",
"b": "bbb",
"c":
{
"d": "ddd",
"e": 123456,
"f": "ffff"
}
}
""")
scala> case class abc(a:String, b:String, c:String)
Solution:1 Would work with 2.3+
scala> implicit val abcdef: Reads[abc] = new Reads[abc] {
def reads(json:JsValue):JsResult[abc] = {
json match {
case o:JsObject if (o.value.get("a").isDefined && o.value.get("b").isDefined && o.value.get("c").isDefined)=>
o.value.get("a").get match {
case JsString(a)=> o.value.get("b").get match {
case JsString(b)=> o.value.get("c").get match {
case c:JsObject if (c.value.get("d").isDefined && c.value.get("e").isDefined && c.value.get("f").isDefined)=>
c.value.get("d").get match {
case JsString(d)=> c.value.get("e").get match {
case JsNumber(e)=> c.value.get("f").get match {
case JsString(f) => JsSuccess(abc(a,b,d+e+f))
case _ =>JsError("some error")
}
case _ =>JsError("some error")
}
case _ =>JsError("some error")
}
case _ =>JsError("some error")
}
case _ =>JsError("some error")
}
case _ =>JsError("some error")
}
case e => JsError("some error")
}
}
}
scala> json.validate[abc]
Solution:2 Will only work with 2.3.x
scala> implicit val abcdef: Reads[abc] = new Reads[abc] {
def reads(json:JsValue):JsResult[abc] = {
json match {
case JsObject(Seq(("a", JsString(a)), ("b", JsString(b)), ("c", jsobj))) => {
jsobj match {
case JsObject(Seq(("d", JsString(d)), ("e", JsNumber(e)), ("f", JsString(f)))) => JsSuccess(abc(a,b,d+e+f))
case _ => JsError("some error")
}
}
case e => JsError("some error" + e)
}
}
}
scala> json.validate[abc]

Answer 2

most common way to achieve this is to combine Reads as explained here:
https://www.playframework.com/documentation/2.3.x/ScalaJsonCombinators
import play.api.libs.json._, Reads.at
import play.api.libs.functional.syntax._
val js = Json.parse("""{
"a": "aaa",
"b": "bbb",
"c": {
"d": "ddd",
"e": 123456,
"f": "ffff"
}
}""")
val transform = {
val c = (__ \ "c");
{
c.json.prune ~
(__ \ "new").json.copyFrom(
at[String](c \ "d") ~
at[Int] (c \ "e") ~
at[String](c \ "f") apply (_ + _ + _) map (JsString)
)
}.apply(_ ++ _).reads(_)
}
transform(js)