Deserialize nested mutable map from with Gson to Kotlin

Question

I cannot convert JSON to Kotlin data class using Gson due to the MutableMap object. The data class

data class MyAction(
    @Key("action") var action: String = "default",
    @Key("data") var data: MutableMap<String, Any> = mutableMapOf()
)

values in the data map are of several types.I tried with TypeToken and Generics, as in here but didn't work. Examples of received json:

1. {"action":"playVideo","data":{"media":{"id":15060328,"url":"http://url_to_get_item","name":"item name","shortDescription":"short desc"}

2. {"action":"setSpeed","data":{"value":1}}

3. {"action":"getProperty","data":{"value":"position"}}

Answer 1

Is not a good practice to design data in that way, but if you have no control on backend here is an example how to deserialize this

class MyDeserializer : JsonDeserializer<MyAction>{
override fun deserialize(json: JsonElement, typeOfT: Type, context: JsonDeserializationContext): MyAction {
    val myAction = MyAction()
    val action = json.asJsonObject.get("action")
    val data = json.asJsonObject.get("data")

    myAction.action = context.deserialize<String>(action, String::class.java)

    val myMap = mutableMapOf<String, Any>()
    data.asJsonObject.keySet().forEach {
        when (it) {
            is String -> { myMap[it] = context.deserialize(data.asJsonObject.get(it), String::class.java) }
            is MyCustomObject1 -> { myMap[it] = context.deserialize(data.asJsonObject.get(it), MyCustomObject1::class.java) }
            is MyCustomObject2 -> { myMap[it] = context.deserialize(data.asJsonObject.get(it), MyCustomObject2::class.java) }
            else -> myMap[it] = context.deserialize(data.asJsonObject.get(it), Any::class.java)
        }
    }

    myAction.data = myMap
    return myAction
}

}

Dont forget to register your deserializer

fun getSmartGson() = GsonBuilder().registerTypeAdapter(MyAction::class.java, MyDeserializer())