SealedClassSerializer

This class provides support for multiplatform polymorphic serialization of sealed classes.

In contrary to PolymorphicSerializer, all known subclasses with serializers must be passed in subclasses and subSerializers constructor parameters. If a subclass is a sealed class itself, all its subclasses are registered as well.

If sealed hierarchy is marked @Serializable, an instance of this class is constructed automatically. In most of the cases, you won't need to perform any manual setup:

@Serializable
sealed class SimpleSealed {
    @Serializable
    public data class SubSealedA(val s: String) : SimpleSealed()

    @Serializable
    public data class SubSealedB(val i: Int) : SimpleSealed()
}

// will perform correct polymorphic serialization and deserialization:
Json.stringify(SimpleSealed.serializer(), SubSealedA("foo"))

However, it is possible to register additional subclasses using regular SerializersModule. It is required when one of the subclasses is an abstract class itself:

@Serializable
sealed class ProtocolWithAbstractClass {
    @Serializable
    abstract class Message : ProtocolWithAbstractClass() {
        @Serializable
        data class StringMessage(val description: String, val message: String) : Message()

        @Serializable
        data class IntMessage(val description: String, val message: Int) : Message()
    }

    @Serializable
    data class ErrorMessage(val error: String) : ProtocolWithAbstractClass()
}

In this case, ErrorMessage would be registered automatically by the plugin, but StringMessage and IntMessage require manual registration, as described in PolymorphicSerializer documentation:

val abstractContext = SerializersModule {
    polymorphic(ProtocolWithAbstractClass::class, ProtocolWithAbstractClass.Message::class) {
        subclass<ProtocolWithAbstractClass.Message.IntMessage>()
        subclass<ProtocolWithAbstractClass.Message.StringMessage>()
        // no need to register ProtocolWithAbstractClass.ErrorMessage
    }
}

Constructors

Properties

Functions