<@U6647LJ30> not sure if I’m running into a compil...

# serialization

[efemoney]

@sandwwraith not sure if I’m running into a compiler bug or its desired behavior but I have a somewhat complex heirarchy I’m trying to serialize with an interface at its apex. Let me see if I can do this justice but my graph looks like:

interface Field<Value> {...}

interface InputField<InputT> : Field<InputT> {...}
interface SelectorField<ValueT> : Field<ValueT> {...}

abstract class NumberField : InputField<Number> {...}
abstract class BooleanField : SelectorField<Boolean> {...}

@Serializable
data class NumberFieldImpl(...): NumberField()

@Serializable
data class BooleanFieldImpl(...): BooleanField()

Also I have a custom _map_:

// Need to add serializable on base class else compiler complains
@Serializable
abstract class MapBackedContainer<K, V>(val storage: MutableMap<K, V>) : MutableMap<K, V> by storage

@Serializable // Currently fails compile, message below
class FieldContainer : MapBackedContainer<String, Field<*>>

@Serializable // This one has no errors, ActionImpl is non generic and annotated with @Serializable
class ActionContainer : MapBackedContainer<String, ActionImpl>

FieldContainer currently fails compile with the message “Serializer for element of type Any? has not been found. To use context serializer as fallback, explicitly annotate element with @Contextual”.

I tried adding @Serializable on the intermediate abstract classes of Field<*> but the issue is the same. Same with adding @Contextual on the Field<*> generic parameter of FieldContainer.

[Dominaezzz]

Polymorphism and generics don't work automatically. You'll have to write the serializers yourself.

[Dominaezzz]

Field<*> hasn't been marked as @Serializable too.

[efemoney]

It’s an interface, the docs say that there is no need to mark it as serializable 🤔

[Dominaezzz]

True but * is not serializable. That's what is refered to as Any?

[sandwwraith]

Indeed, since Field<Value> does not specify upper bound, Field<*> is a Field<Any?> for serialization framework. You may try Field<@Polymorphic Any> instead.

[efemoney]

Is this in the Field interface definition or at the use-site (in the generic type parameter of FieldContainer)?

[sandwwraith]

on a use-site

[efemoney]

Ignore this for now, I dont think Country is Serializable. Thanks for the help @sandwwraith @Dominaezzz 🙏

[sandwwraith]

Change override var name: String = id.capitalize(Locale.ROOT) to override val name: String get() = .... It's an old bug (https://github.com/Kotlin/kotlinx.serialization/issues/133) 😞

[efemoney]

Ohhhh, that is exactly the issue!

[efemoney]

Thanks!

[efemoney]

(Posting the message again so people dont lose context)