kotlinlang #klaxon

I'm at a loss. is there a sample of a native kotlin project somewhere that uses klaxon? am I wrong to assume that I can use klaxon in a mingw windows build?

jk2018

11/26/2019, 11:34 PM

I guess, the reason is that Klaxon depends on Java?

cedric

11/27/2019, 3:49 PM

Yes, Klaxon relies on JVM specific libraries, I haven't looked into making it MPP

jk2018

11/27/2019, 6:20 PM

Thanks for the clarification. May I suggest adding a one line into the readme to mention that it will only work on JVM? Wasn't clear to me, especially since Java or jvm is not mentioned in the readme. Also possible that I missed something. Thx!

cedric

11/27/2019, 6:32 PM

Sure. I think Kotlin projects are considered by default as being JVM only since multi platform is not something you typically think about when you start a Kotlin project

jk2018

11/27/2019, 9:16 PM

True of course. Thx!

LeoColman

12/01/2019, 12:30 AM

Hey mister

LeoColman

12/01/2019, 12:31 AM

Do you need any help on https://github.com/cbeust/klaxon/issues/154?

LeoColman

12/01/2019, 12:31 AM

It's a real blocker for me to use Klaxon due to it at the moment

LeoColman

12/01/2019, 12:31 AM

I'm not very familiar with Klaxon's code base, but I'm very eager to help you if I can

Byron Woodfork

12/02/2019, 10:25 PM

Question in regads to the @TypeFor annotation. If the type that I'm parsing isn't caught in the

when

clause, I just want to do nothing. As opposed to throwing an exception. Or is there a graceful way to catch the exception once it's thrown? Pretty sure I'm confusing myself because of the way this is laid out.

viralshah

02/14/2020, 4:28 AM

does anyone know how I can add a element to the

notes

array in the following json object?

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val msg = json { obj( "a" to "b", "notes" to array() ) }

Andrew Giorgio

02/17/2020, 8:17 PM

Hi! I'm having some trouble getting polymorphic classes to work with the Object Binding API. I copied the example from the readme exactly, but when I try to parse the json, I get

Unable to instantiate Rectangle with parameters []

as an error. As far as I can tell, it expects the width and height fields to exist on the Shape class itself. Does anyone know why this might be?

cedric

02/17/2020, 8:21 PM

@Andrew Giorgio Can you share some of your sources?

Andrew Giorgio

02/17/2020, 8:23 PM

I define these classes:

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@TypeFor(field = "type", adapter = ShapeTypeAdapter::class)
open class Shape(val type: String)

data class Rectangle(val width: Int, val height: Int) : Shape("rectangle")
data class Circle(val radius: Int) : Shape("circle")
class ShapeTypeAdapter : TypeAdapter<Shape> {
    override fun classFor(type: Any): KClass<out Shape> = when (type as String) {
        "rectangle" -> Rectangle::class
        "circle" -> Circle::class
        else -> throw IllegalArgumentException("Unknown type: $type")
    }
}

and then I call the following (in a test), which gives me the error.

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val result = Klaxon().parseArray<Shape>(
        """
            [
                { "type": "rectangle", "width": 100, "height": 50 },
                { "type": "circle", "radius": 20}
            ]
         """
)

Andrew Giorgio

02/17/2020, 8:24 PM

I'm using Kotlin 1.3.11 and Klaxon 5.0.1.

cedric

02/18/2020, 12:40 AM

@Andrew Giorgio That example works fine out of the box for me. I added a

println(result)

at the end and I get:

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[Rectangle(width=100, height=50), Circle(radius=20)]

Andrew Giorgio

02/21/2020, 12:06 AM

Hmm, do you have any idea why it might not be working for me? I've been playing around with it, and it looks like the parsing process is trying to set the width and height fields on Shape by default. I have an example of how it's not working: I've modified my classes to the following:

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import com.beust.klaxon.TypeAdapter
import com.beust.klaxon.TypeFor
import kotlin.reflect.KClass

@TypeFor(field = "type", adapter = ShapeTypeAdapter::class)
open class Shape(val type: String) {
    val width: Int = -1
    val height: Int = -1
    val radius: Int = -1
}

class Rectangle(width: Int, height: Int) : Shape("rectangle")
class Circle(radius: Int) : Shape("circle")
class ShapeTypeAdapter : TypeAdapter<Shape> {
    override fun classFor(type: Any): KClass<out Shape> = when (type as String) {
        "rectangle" -> Rectangle::class
        "circle" -> Circle::class
        else -> throw IllegalArgumentException("Unknown type: $type")
    }
}

This allows the parse to happen without errors. However, the results are unexpected. I wrote the following test, and put the results of the print statements in comments on the same line:

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val result = Klaxon().parseArray<Shape>(
        """
            [
                { "type": "rectangle", "width": 25, "height": 75},
                { "type": "circle", "radius": 20}
            ]
         """
)
println(result?.get(0)?.width) //Prints 25
println(result?.get(0)?.height)//Prints 75

However, based on my understanding of how this code should work, the actual width and height parameters that were read from the JSON string should be unused, and the print statements should both output -1. Especially as the width and height properties on Shape are neither mutable nor open.

Gunslingor

04/03/2020, 5:04 PM

Any new info on how one can pretty print these days? prettyPrint is red:

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Klaxon().toJsonString(Reports.get(reportID!!), prettyPrint = true)

Gunslingor

04/04/2020, 11:46 PM

Does klaxon act as a replacement for jackson? Like the Create Ktor Section of this: https://ryanharrison.co.uk/2018/04/14/kotlin-ktor-exposed-starter.html

cedric

04/05/2020, 12:02 AM

@Gunslingor No, it's not...

mathew murphy

05/01/2020, 4:06 PM

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Exception in thread "pool-1-thread-1" java.util.ConcurrentModificationException
        at java.base/java.util.ArrayList$Itr.checkForComodification(ArrayList.java:1042)
        at java.base/java.util.ArrayList$Itr.next(ArrayList.java:996)
        at com.beust.klaxon.World.foundValue$klaxon(World.kt:109)
        at com.beust.klaxon.KlaxonParser$1$7.invoke(KlaxonParser.kt:116)
        at com.beust.klaxon.KlaxonParser$1$7.invoke(KlaxonParser.kt:9)
        at com.beust.klaxon.StateMachine.next(StateMachine.kt:20)
        at com.beust.klaxon.KlaxonParser.fullParseLoop(KlaxonParser.kt:63)
        at com.beust.klaxon.KlaxonParser.parse(KlaxonParser.kt:25)

cedric

05/01/2020, 4:08 PM

Can you file an issue with the steps to reproduce this?

mathew murphy

05/01/2020, 4:11 PM

Not easily, I'm afraid. It's happening in a complex multithreaded program that takes 30 minutes to crash.

cedric

05/01/2020, 4:11 PM

Make sure you are using different Klaxon objects if parsing on different threads

mathew murphy

05/01/2020, 4:14 PM

Ah, that could be it.

mathew murphy

05/01/2020, 4:15 PM

Yes, looks like I have three Mapper objects but the class keeps a single Klaxon class instance.

cedric

05/01/2020, 4:15 PM

Pretty sure that's why, although that CM exception is not necessarily caused by multithreading

mathew murphy

05/01/2020, 7:23 PM

OK, giving each object its own Klaxon seems to have stopped the crash.

mathew murphy

05/01/2020, 7:43 PM

Though now the program isn't exiting when it's done for some reason...