Hi, is it possible to override serializer? I have a library class annotated as `@Serializable` but ...

# serialization

[Tomas Kormanak]

Hi, is it possible to override serializer? I have a library class annotated as @Serializable but I would like to use different serializer than default one but I can't change the library code.

[Emil Kantis]

Depends a bit on your use case. You can always specify the serializer explicitly when encoding/decoding if it's the immediate element you're trying to encode/decode. If it's nested in a structure you don't control it gets trickier..

see https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/serializers.md#serializing-3rd-party-classes

[Tomas Kormanak]

I can't set serializer when calling encode, I don't call it directly

[Emil Kantis]

if the library class is nested in a structure you own you could override it that way, see: https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/serializers.md#specifying-serializer-on-a-property

[Emil Kantis]

Are you using some framework which performs the serialization then?

[Tomas Kormanak]

Ktor & Kmongo, both use kotlinx.serialization

[Emil Kantis]

I'm not aware of any explicit ways to set the serializer of a specific class when constructing Json serializer sadly.. Could've been handy in this case? 🙂

Json {
  useSerializerForClass<MyLibClass>(CustomLibSerializer)
}

Perhaps there's some GH issue for it

[Tomas Kormanak]

It would be great! Even better if it was possible to set it in serializer module

[Emil Kantis]

Let me know if you find or create an issue.. I'd add a thumbs up to it blob joy

[Tomas Kormanak]

https://github.com/Kotlin/kotlinx.serialization/issues/1952

[ephemient]

the serialization format has influence over @Contextual and @Polymorphic serialization because the containing classes' serializers look up the members' serializers via serializersModule, but that's not true for other members. serializers for generics are passed as constructor parameters and all others are referenced directly, the serial format has no influence over that.