jackson-module-kotlin-issue-130

FooTest.kt

package com.example

import com.fasterxml.jackson.databind.DeserializationFeature
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.SerializationFeature
import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
import com.fasterxml.jackson.module.kotlin.readValue
import org.junit.jupiter.api.Test

/**
 * see: https://github.com/FasterXML/jackson-module-kotlin/issues/130
 */
class FooTest {

    @Test
    fun testA() {
        val source =  "{}"
        doIt(source)
    }
    @Test
    fun testB() {
        val source =  """ {"s":null} """
        
        // will fail: JSON.readValue<FooNotNullable>(source)
        doIt(source)
    }

    private fun doIt(source:String) {
        println("==== source: $source ====")

        JSON.readValue<FooNullable>(source)
                .also {
                    println("fooNullable: $it")
                    println("fooNullable.toJson(): ${JSON.writeValueAsString(it)}")
                }

        JSON.readValue<FooNotNullable>(source)
                .also {
                    println("fooNotNullable: $it")
                    println("fooNotNullable.toJson(): ${JSON.writeValueAsString(it)}")
                }
    }
}

private val JSON:ObjectMapper = defaultMapper()
private data class FooNullable(val s:String?="default", val i:Int?=100)
private data class FooNotNullable(val s:String="default", val i:Int=100)

private fun defaultMapper(): ObjectMapper = jacksonObjectMapper()
        .findAndRegisterModules()
        // toJson()
        .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
        .disable(SerializationFeature.WRITE_DURATIONS_AS_TIMESTAMPS)
        // fromJson()
        .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
        .disable(DeserializationFeature.ACCEPT_EMPTY_ARRAY_AS_NULL_OBJECT)
        .disable(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT)
        .disable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY)
        .enable(DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES)
        .enable(DeserializationFeature.FAIL_ON_NUMBERS_FOR_ENUMS)