Deserialization of Maps with any key type

[lambdaknight]

Right now, Jerkson only supports deserializing maps with a String, Int, or Long key. Please support deserializing maps with any type of key.

[sroebuck]

I think I'm encountering this issue.

I want to parse the following:

val s = """{"event":"form","id":"xsD7n7h4rPem6pg0M1Bv19r","data":[{"name":"name","value":"Fred Bloggs"},{"name":"email","value":"fred@company.com"}]}"""

Trying this with jerkson (com.codahale.jerkson.Json.parse(s)) gives:

java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to scala.runtime.Nothing$
    at .<init>(<console>:10)
    at .<clinit>(<console>)
    at .<init>(<console>:11)
    at .<clinit>(<console>)
    at $print(<console>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:704)
    at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:914)
    at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:546)
    at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:577)
    at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:543)
    at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:694)
    at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:745)
    at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:651)
    at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:542)
    at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:550)
    at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822)
    at scala.tools.nsc.interpreter.ILoop.main(ILoop.scala:851)
    at xsbt.ConsoleInterface.run(ConsoleInterface.scala:57)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:57)
    at sbt.compiler.AnalyzingCompiler.console(AnalyzingCompiler.scala:48)
    at sbt.Console.console0$1(Console.scala:23)
    at sbt.Console$$anonfun$apply$2$$anonfun$apply$1.apply$mcV$sp(Console.scala:24)
    at sbt.TrapExit$.executeMain$1(TrapExit.scala:33)
    at sbt.TrapExit$$anon$1.run(TrapExit.scala:42)

However, using the twitter Json parser (com.twitter.json.Json.parse(s)) correctly gives:

Map(event -> form, id -> xsD7n7h4rPem6pg0M1Bv19r, data -> List(Map(name -> name, value -> Fred Bloggs), Map(name -> email, value -> fred@company.com)))

[sroebuck]

I have found that I can get most of the way with deserialising maps using:

Json.parse[Map[String, JValue]](json)

for a map between a String key and any kind of value. The resulting JValue needs post-processing but it's mostly useable. However, problems come up as soon as I have a JSON string containing the String or value "null". The above line then gives the error:

com.codahale.jerkson.ParsingException: Can not deserialize instance of com.codahale.jerkson.AST$JValue out of VALUE_NULL token

It seems that it doesn't support "null" as a valid JValue in this context.

[sroebuck]

Okay, this isn't perfect, but with Coda's assistance I have discovered that Jerkson supports Option types, so, in the above example:

Json.parse[Map[String, Option[JValue]]](json)

works nicely, but for a fuller explanation see my comment on another issue here: #41 (comment)

[aloiscochard]

What about fixing this? 8 months old...