Kotlin Serialization: advanced patterns with Polymorphic Types in JSON Deserialization
Does anyone know how to I'm deploying to production and I'm relatively new to this, so bear with me... I'm working with an scenario with Kotlin serialization when trying to deserialize a polymorphic type from JSON. I have a sealed class hierarchy for different shapes, and I want to deserialize JSON into the appropriate subclass automatically. Here’s what my code looks like: ```kotlin import kotlinx.serialization.* import kotlinx.serialization.json.* @Serializable sealed class Shape { @Serializable data class Circle(val radius: Double) : Shape() @Serializable data class Rectangle(val width: Double, val height: Double) : Shape() } val json = Json { polymorphic { Shape::class subclass(Shape.Circle::class, Shape.Circle.serializer()) subclass(Shape.Rectangle::class, Shape.Rectangle.serializer()) }} fun main() { val jsonString = "{ \"type\": \"Circle\", \"radius\": 5.0 }" val shape: Shape = json.decodeFromString(jsonString) println(shape) } ``` However, when I try to deserialize this JSON string, I get the following behavior: ``` SerializationException: Encountered an unknown polymorphic type: Circle ``` I’ve ensured that I’m using `kotlinx.serialization:1.3.0` and have added the necessary annotations. I suspect that the scenario might be in how I'm defining the polymorphic behavior, particularly with the `type` field in my JSON not matching expected subclass identifiers. I’ve tried adding a custom serializer but haven’t had much luck. What could I be missing to properly map the JSON fields to my sealed class? Any tips or examples would be greatly appreciated! I'm coming from a different tech stack and learning Kotlin. Is there a simpler solution I'm overlooking? I'd love to hear your thoughts on this. The project is a REST API built with Kotlin.