Klaxon cannot deserialize to or from raw strings

In Klaxon 2.0.10:

• If an object serializes to a string, it cannot be deserialized
• cannot deserialize a list of strings

    data class Person(val id: String, val firstName: String)

    /** This converter serializes a person to a string **/
    class PersonConverter: Converter<Person> {
        override fun toJson(value: Person) = "\"${value.id}:${value.firstName}\""
        override fun fromJson(jv: JsonValue) = jv.string?.let {
            val (id, firstName) = it.split(":")
            Person(id, firstName)
        } ?: throw KlaxonException("Invalid Person: $jv")
    }

    @Test
    fun deserializeStringListToObjectList() {
        val mapper = Klaxon().converter(PersonConverter())
        val obj = listOf(Person("1", "John"))

        val jv = mapper.toJsonString(obj)
        Assert.assertThat(jv, CoreMatchers.equalTo("[1:John]")) // Passes
        Assert.assertThat(mapper.parse(jv), CoreMatchers.equalTo(obj)) // Fails
    }

    @Test
    fun deserializeStringToObject() {
        val mapper = Klaxon().converter(PersonConverter())
        val obj = Person("1", "John")

        val jv = mapper.toJsonString(obj)
        Assert.assertThat(jv, CoreMatchers.equalTo("1:John")) // Passes
        Assert.assertThat(mapper.parse(jv), CoreMatchers.equalTo(obj))  // Fails
    }

    @Test
    fun deserializeStringListToStringList() {
        val obj = listOf("foo", "bar", "baz")
        val mapper = Klaxon()

        val jv = mapper.toJsonString(obj)
        Assert.assertThat(jv, CoreMatchers.equalTo("[\"foo\", \"bar\", \"baz\"]")) // Passes
        Assert.assertThat(mapper.parse(jv), CoreMatchers.equalTo(obj)) // Fails
    }

Now I get:

java.lang.ClassCastException: java.lang.String cannot be cast to com.beust.klaxon.JsonObject

    at com.prontoforms.pcns.auth.authorizer.MethodArnUnitTest.deserializeStringToObject(MethodArnUnitTest.kt:181)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

or

java.lang.ClassCastException: com.beust.klaxon.JsonArray cannot be cast to com.beust.klaxon.JsonObject

    at com.prontoforms.pcns.auth.authorizer.MethodArnUnitTest.deserializeStringListToObjectList(MethodArnUnitTest.kt:180)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

[oharaandrew314]

Ok, it obviously is wrong to serialize an object to a plain string. I’ll close and re-open with the real problem.

[oharaandrew314]

There was indeed a mistake in my serializer. I needed to surround the result in quotes. I now no longer get parsing exceptions, but I still get cast exceptions. It seems that your converter only allows json objects to be at the root of a document, when, in reality, a json array can be a valid start of the document.