Parsing complex JSON with JSON Combinators in Play - json

Question

I'm trying to parse the data from GovTrack, for example, https://www.govtrack.us/api/v2/bill/74369 . But titles is in a peculiar format:
"titles": [
[
"short",
"introduced",
"Public Online Information Act of 2011"
],
[
"official",
"introduced",
"To establish an advisory committee to issue nonbinding governmentwide guidelines..."
]
]
titles is an array of each title type, with fields in a particular order. I want to read this into a more standard JSON format:
{
'short_title': "Public Online Information Act of 2011",
'official_title': "To establish an advisory committee to issue nonbinding governmentwide guidelines..."
}
The short title or official title may or may not be there, and there could actually be several short titles.
How do I make a Reads for this? Right now I've got:
implicit val billReads: Reads[Bill] = (
(JsPath \ "id").read[Int] and
(JsPath \ "display_number").read[String] and
(JsPath \ "current_status").read[String] and
(JsPath \ "titles")(0)(2).read[String]
)(Bill.apply _)
How do I specify "The member of the array that has a first element equal to 'official'"?

Answer 1

As far as I know, there is no out of the box way to do it, but I would do it with additional custom reader, like this:
val officialReads = new Reads[String] {
override def reads(json: JsValue): JsResult[String] = (json \ "titles") match {
case JsArray(titles) => titles.collectFirst({
case JsArray(values) if (values.headOption.map(v => "official".equals(v.as[String])).getOrElse(false)) =>
JsSuccess(values.tail.tail.head.as[String])
}).getOrElse(JsError("No official title"))
case _ => JsError("Can't read official title")
}
}
And your Bill reader would look like this:
val implicitReads: Reads[Bill] = (
(__ \ "id").read[Int] and
(__ \ "display_number").read[String] and
(__ \ "current_status").read[String] and
officialReads
)(Bill.apply _)
I've tested, this works :)