👀 Views: 80 💬 Answers: 1 📅 Created: 2025-06-15

kotlin serialization kotlinx.serialization Kotlin

I'm working with a question with serializing and deserializing nested data classes using kotlinx.serialization in Kotlin. I have a parent data class that contains a list of child data classes, and I need to ensure that all properties are correctly serialized to JSON and then deserialized back to their original types. However, I'm running into an scenario where the child classes are not being properly recognized during deserialization. Here's a simplified version of my code: ```kotlin import kotlinx.serialization.* import kotlinx.serialization.json.* @Serializable data class Child(val name: String, val age: Int) @Serializable data class Parent(val id: Int, val children: List<Child>) fun main() { val json = Json { ignoreUnknownKeys = true } val parent = Parent(1, listOf(Child("Alice", 10), Child("Bob", 12))) val jsonString = json.encodeToString(parent) println(jsonString) // Simulating deserialization val deserializedParent = json.decodeFromString<Parent>(jsonString) println(deserializedParent) } ``` When I run this code, the serialization works fine, and I get a JSON string as expected. However, when deserializing, I'm getting the following behavior: ``` SerializationException: Expected a class descriptor for the type 'Child' but found a different type. ``` I’ve checked that the `@Serializable` annotation is present on both data classes, and I am using kotlinx.serialization version 1.3.0. I also verified that I am importing the correct Json classes. What could be causing this behavior? Is there a specific way I should be structuring my data classes or configuring the Json instance to handle nested serialization/deserialization correctly? Any insights would be greatly appreciated!