Testing Lift-4 with json4s

[Andreas Joseph Krogh]

Hi all.

 

We're testing the lates Lift-4.0-branch, with Scala-2.13, and some changes in json4s causes us trouble.

 

We've persisted serialized values, which we need to load from DB and deserialize. These values can be everything from case class-es to primitives.

 

Take this example:

 

@Test
def testParseBoolean(): Unit = {
    implicit val formats = DefaultFormats.lossless
    val jValue = Extraction.decompose(true)
    val jsonString = JsonMethods.compact(JsonMethods.render(jValue))
    println(jsonString)
    val parsedValue = JsonParser.parse(jsonString)
    println(parsedValue)
}

 

The serialized value is true, but trying to deserialize the value true (parse("true")) results in:

 

org.json4s.ParserUtil$ParseException: expected field or array
Near: true

 

It's quite inconvenient that it doesn't manage to deserialize the output of the serializer to the same value.

 

Anyone knows a way to fix this?

 

--

Andreas Joseph Krogh

CTO / Partner - Visena AS

Mobile: +47 909 56 963

and...@visena.com

www.visena.com

[Andreas Joseph Krogh]

Seems json4s' has JsonParser.newValue defined as:

def newValue(v: JValue): Unit = {
  vals.peekAny match {
    case (name: String, _) =>
      vals.pop(classOf[JField])
      val obj = vals.peek(classOf[JObject])
      vals.replace(JObject((name, v) :: obj.obj))
    case a: JArray => vals.replace(JArray(v :: a.arr))
    case _ => p.fail("expected field or array")
  }
}

 

While lift-json has:

def newValue(v: JValue) {
  if (!vals.isEmpty)
    vals.peekAny match {
      case JField(name, value) =>
        vals.pop(classOf[JField])
        val obj = vals.peek(classOf[IntermediateJObject])
        obj.fields += (JField(name,v))
      case a: IntermediateJArray => a.bits += v
      case other => p.fail("expected field or array but got " + other)
  } else {
    vals.push(v)
    root = Some(v)
  }
}

 

So, for some reason the json4s-team thought it would be fine to just skip “raw fields”….

 

Anyone familiar with this?

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[Matt Farmer]

I suspect this is because json4s forked from lift-json a long time ago. Lucky for us we know someone who is a committer for json4s too. :) (me)

This is on my radar. Let me do some research and update here after. 

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[Andreas Joseph Krogh]

Sounds very good, thanks!

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[Andreas Joseph Krogh]

Attached patch implements this.

 

Any chance of getting it merged upstream?

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[Matt Farmer]

You beat me to it. I've been in crisis mode all week. 🙃

Let me have a look.

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[Matt Farmer]

https://github.com/json4s/json4s/pull/1772

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[Andreas Joseph Krogh]

🎸👍

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