generate a json structure from fields in scala - json

Question

I would like to create a json string from several fields in scala.
the different fields are retrieved from a text file:
import scala.io.Source
val source = Source.fromFile("D:/Web/Data/QueueFile/FromCarrier/00001709.status.201808010837422.txt")
val lines = source.getLines()
while (lines.hasNext){
val newLine = lines.next()
println(newLine)
val arrayLine = newLine.split(";").toArray
val MatchingField = arrayLine(1)
val TStatus_Code = arrayLine(0)
val Trace_Date = arrayLine(2)
println("MatchingField: " + MatchingField + " - TStatus_Code: " + TStatus_Code + " - Trace_Date: " + Trace_Date)
if(TStatus_Code.nonEmpty && Trace_Date.nonEmpty){
println("TStatus_Code and Trace_Date exist, we should build the json structure")
**val MQS.Trace.Trace_Date = Trace_Date
val MQS.Trace.TStatus_Code = TStatus_Code
val MQS.MatchingField = MatchingField
val MQS.Provider_ID = 1
val MQS.Customer_ID = 989
val QMessage = SerializeJson(MQS)**
}
else
println("TStatus_Code and/or Trace_Date does not exist, don't generate the json structure")
}
The code between ** works in another langage (coldfusion). I would like to do the same thing in scala.
Any help would be much appreciated. Thanks

Answer 1

There are two parts to this question:
1. How to represent the data
2. How to serialize it to json
For the first part, you can create a case class and fill it with your data, e.g.:
case class MQS(traceDate: String, tStatusCode: String, matchingField: String, providerId: Int, customerId: Int)
val mqs = MQS(Trace_Date, TStatus_Code, MatchingField, 1, 989)
For the second part you can use any of many json serializers. A simple example would be with json4s (http://json4s.org/):
import org.json4s.DefaultFormats
import org.json4s.native.Serialization.write
write(mqs)(DefaultFormats)
EDIT
The case class needs to be defined in an object. Following is a full example:
import org.json4s.DefaultFormats
import org.json4s.native.Serialization.write
object App {
case class MQS(traceDate: String, tStatusCode: String, matchingField: String, providerId: Int, customerId: Int)
def main(args: Array[String]): Unit = {
println("Hello, world!")
val mqs = MQS("Trace_Date", "TStatus_Code", "MatchingField", 1, 989)
println(write(mqs)(DefaultFormats))
}
}
The case class definition cannot be inside the function main (or any method/class) but instead must be in an object.