Kotlin vert.x parsing a JSON String to a Data class using gson always returns null - kotlin

Question

I am just playing around with vert.x 3.5.3 Kotlin and I am unable to parse a JSON string into a Data class using gson.
Here is the code
class DataVerticle : AbstractVerticle() {
override fun start(startFuture: Future<Void>) {
data class Product(
#SerializedName("id") val id: Int,
#SerializedName("name") val name: String,
#SerializedName("productCode") val productCode: String
)
val products: MutableList<Product> = mutableListOf()
val gson = Gson()
val eventBus = vertx.eventBus()
eventBus.consumer<String>("data.verticle") {
when (it.headers().get("ACTION")) {
"ADD_PRODUCT" -> {
val prodJson = it.body()
if (prodJson != null) {
println(prodJson)
val product = gson.fromJson(prodJson, Product::class.java)
println(product)
it.reply("SUCCESS")
}
}
else -> {
print("ERROR")
}
}
}
startFuture.complete()
}
}
The Problem is the parsed value is always null
Here is my sample json ->
{"id":1,"name":"SOAP","productCode":"P101"}
The json string sent over the eventBus is not null.
I am using this package for gson
com.google.code.gson', version: '2.8.5'
Thanks

Answer 1

You declare your class inside the method body, which Gson doesn't like much.
Extracting it to be nested class will work just fine:
class DataVerticle : AbstractVerticle() {
override fun start(startFuture: Future) {
val gson = Gson()
val eventBus = vertx.eventBus()
eventBus.consumer<String>("data.verticle") {
when (it.headers().get("ACTION")) {
"ADD_PRODUCT" -> {
val prodJson = it.body()
if (prodJson != null) {
println(prodJson)
val product = gson.fromJson(prodJson, Product::class.java)
println(product)
it.reply("SUCCESS")
}
}
else -> {
print("ERROR")
}
}
}
startFuture.complete()
}
data class Product(
#SerializedName("id") val id: Int,
#SerializedName("name") val name: String,
#SerializedName("productCode") val productCode: String
)
}
Tested with:
val vertx = Vertx.vertx()
vertx.deployVerticle(DataVerticle()) {
val options = DeliveryOptions()
options.addHeader("ACTION", "ADD_PRODUCT")
vertx.eventBus().send("data.verticle", """{"id":1,"name":"SOAP","productCode":"P101"}""", options)
}