Parsing/extracting information from JSON in Scala - json

Question

I'm trying to extract (timestamp, value) tuples from this third party JSON message:
{
"data": {
"1496845320000": [
0.14
],
"1496845380000": [
0.14
],
"1496845560000": [
0.14
],
"1497013740000": [
"undef"
],
"1497013800000": [
"undef"
],
"1497013860000": [
"undef"
]
},
"status": "ok"
}
This is how I'm extracting the JSON entity:
val batchReadings = http.singleRequest(httpRequest) map {
case HttpResponse(StatusCodes.OK, headers, entity, _) =>
entity.dataBytes.runFold(ByteString(""))(_ ++ _).foreach { body =>
JSON.parseFull(body.utf8String) match {
case Some(e: Map[String, Any]) =>
e.get("status") match {
case Some("ok") => println("ok!")
e.get("data") match {
case Some(f: Map[String, List[Any]]) =>
println("entered second case")
new EfergyReadingsData(f.toList).getReadings
}
case _ => log.info("EfergyReaderWorkerActor: Received unknown message\n" + body.utf8String)
}
}
}
case HttpResponse(code, _, entity, _) =>
//entity.toStrict(100, materializer) N.B. Not having this, will freeze after 4 calls!
s"Response code: $code"
case unknown =>
s"unknown response: $unknown"
}
And this is the EfergyReadingsData class:
class EfergyReadingsData(readings: List[(String, List[Any])]) {
def getReadings: List[(Long, Double)] = {
println(readings)
// List((1123, 34.4))
val filteredReadings = readings filter {
f =>
f._2 match {
case t:List[Any] =>
t.head match {
case Double => true
case _ => false
}
}
}
val theRead = filteredReadings map {
p => (p._1.toLong, p._2.head)
}
println(theRead)
List((1123, 34.4))
}
}
As you can see I'm not returning the List of tuples that I'm supposed to in getReadings, I just created a list to be returned so I could test the code.
Besides not being able to filter the list to remove only the undefentries (the filteredReadings is empty), the first obvious problem with this approach is that I'm pattern matching for types inside List and Map and therefore getting a warning about those being unchecked because they are eliminated by erasure.
Although not represented above for simplicity, I tried to mitigate this by using case classes for the Lists:
sealed abstract class AnyReading {
val value: List[Any]
}
case class SuccessfulReading(override val value: List[Double]) extends AnyReading
case class FailedReading(override val value: List[String]) extends AnyReading
So, to conclude, what is the best way to go about this? I also thought of creating few case classes to represent the the JSON structure and try to deserialise the JSON message and then filter to remove the undef values, and ultimately get the list of tuples I wanted.
Thank you in advance for your help.