CODEWITHSUNDEEP
serializationkotlindeserializationkotlin-extensionjson-serialization
rhythm
rhythm

Reputation: 499

Kotlin - Serialize JSON Array to multiple classes

I'd like to parse JSON Array(in String) to Kotlin Array of multiple classes. Is it possible to do serialization like below? I'm using kotlinx.serialization, but can use other libraries if needed.

abstract class DataTypeBase(val dataType: DataTypeEnum) {
    abstract fun doSomething()
}

@Serializable
data class DataTypeA(dataType: DataTypeEnum, val a: String): DataTypeBase(dataType) {}

@Serializable
data class DataTypeB(dataType: DataTypeEnum, val b: Int) : DataTypeBase(dataType) {}

fun customSerializer(): KSerializer {
    when (json.dataType) {
        DataTypeEnum.A -> return DataTypeA.serializer()
        DataTypeEnum.B -> return DataTypeB.serializer()
    }
}

fun run() {
    val dataArray: Array<DataTypeBase> = 
         Json().parse(ArrayListSerializer(customSerializer(), jsonArrayInString) 
}

For example, 

[{ dataType: "A", a: "text" }, { dataType: "B", b: 123 }]

becomes

Array[0] : DataTypeA("A", "text")
Array[1] : DataTypeB("B", 123)

Upvotes: 1

Views: 2855

Answers (1)

Markus
Markus

Reputation: 46

You may use the following:

@Serializable
abstract class DataTypeBase()

@Serializable
data class DataTypeA(val a: String) : DataTypeBase()

@Serializable
data class DataTypeB(val b: Int) : DataTypeBase()

fun main() {
    val format = Json(context = SerializersModule {
        polymorphic(DataTypeBase::class) {
            DataTypeA::class with DataTypeA.serializer()
            DataTypeB::class with DataTypeB.serializer()
        }
    })
    val string = format.stringify(DataTypeBase.serializer().list, listOf(DataTypeA("text"), DataTypeB(123)))
    println(string)
    println(format.parse(PolymorphicSerializer(DataTypeBase::class).list, string))
}

output

[{"type":"DataTypeA","a":"text"},{"type":"DataTypeB","b":123}]
[DataTypeA(a=text), DataTypeB(b=123)]

Upvotes: 2

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