com.fasterxml.jackson.module.kotlin.KotlinBeanDeserializerModifier.kt Maven / Gradle / Ivy

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Add-on module for Jackson (https://github.com/FasterXML/jackson/) to support Kotlin language, specifically introspection of method/constructor parameter names, without having to add explicit property name annotation.

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package com.fasterxml.jackson.module.kotlin

import com.fasterxml.jackson.databind.BeanDescription
import com.fasterxml.jackson.databind.DeserializationConfig
import com.fasterxml.jackson.databind.JsonDeserializer
import com.fasterxml.jackson.databind.deser.BeanDeserializerModifier

// [module-kotlin#225]: keep Kotlin singletons as singletons
object KotlinBeanDeserializerModifier : BeanDeserializerModifier() {
    override fun modifyDeserializer(
            config: DeserializationConfig,
            beanDesc: BeanDescription,
            deserializer: JsonDeserializer<*>
    ): JsonDeserializer {
        val modifiedFromParent = super.modifyDeserializer(config, beanDesc, deserializer)

        val objectSingletonInstance = objectSingletonInstance(beanDesc.beanClass)
        return if (objectSingletonInstance != null) {
            KotlinObjectSingletonDeserializer(objectSingletonInstance, modifiedFromParent)
        } else {
            modifiedFromParent
        }
    }
}

private fun objectSingletonInstance(beanClass: Class<*>): Any? = if (!beanClass.isKotlinClass()) {
    null
} else {
    beanClass.kotlin.objectInstance
}