I need to parse Json into Map[String,String] structure. Json may contain numeric and string types as values.
So in order to store it as String I've applied toString method and it throws ClassCastException. However if String.valueOf() is applied everything is OK.
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.scala.DefaultScalaModule
import scala.collection.Map
import scala.util.parsing.json.JSON
val mapper = new ObjectMapper()
mapper.registerModule(DefaultScalaModule)
val str = "[ { \"name\": \"VehicleType\", \"value\": 11 }, { \"name\": \"VehicleWeight\", \"value\": \"12000\" } ]"
val customfields = JSON.parseFull(str) match {
case Some(map: List[Map[String, String]]) =>
// map.map(map => {map("name") -> map("value").toString}).toMap
// that throws:
// java.lang.ClassCastException: java.lang.Double cannot be cast to java.lang.String
// at #worksheet#.$anonfun$customfields$1.apply(scratch.scala2:14)
// at #worksheet#.$anonfun$customfields$1.apply(scratch.scala2:14)
// at scala.collection.immutable.List.map(scratch.scala2:269)
// at #worksheet#.customfields$lzycompute(scratch.scala2:14)
// that works fine
map.map(map => {map("name") -> String.valueOf(map("value"))}).toMap
case _ => Map.empty[String, String]
}
Because the pattern matching match the List type, but doesn't go all the way to all types inside the map, that's why you enter the Some
clause.
So, instead of the case Some(map: List[Map[String, String]]) =>
Try do this:
case Some(map: List[Map[String, _]]) =>
map.map(map => {map("name") ->
map("value") match {
case s: String => s
case i: java.lang.Number => i
case unexpectedType => throw Exception(s"Unexpected type $unexpectedType")
}.toString}).toMap
That's how you can handle every value in your map safely.
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