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How/Can I use a custom KSerializer?

See original GitHub issue

Is it possible to use a custom defined KSerializer to store an object that does not have the @Serializable annotation defined? For example, let’s say I want to store a Date using the kotlinxPref delegate – basing this on the example.

I’ve defined a KSerializer in my Kotlin file.


object DateAsLongSerializer : KSerializer<Date> {
    override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("Date", PrimitiveKind.LONG)
    override fun serialize(encoder: Encoder, value: Date) = encoder.encodeLong(value.time)
    override fun deserialize(decoder: Decoder): Date = Date(decoder.decodeLong())

And created a SerializersModule so that I can set that in the json extension property.

val module = SerializersModule {

And then defined a SimpleKrate as;

class DateKrate(context: Context) : SimpleKrate(context) {
        init {
            json = Json { serializersModule = module }

        var currentDate: Date? by kotlinxPref("current-date")

But when I try to assign a value to that Krate I get the following exception. Serializer for class 'Date' is not found. Mark the class as @Serializable or provide the serializer explicitly.

Any ideas of what I might be doing wrong here? (Thanks for creating this great library btw)

Edit: The alternative is to just store it as a private longPref and define a getter/setter which casts the value to and from a long. Just curious though on the use of the KSerializer.

Issue Analytics

  • State:closed
  • Created 2 years ago
  • Comments:10

github_iconTop GitHub Comments

zsmb13commented, Sep 24, 2021

Ah, got it. Back in 1.0.0, the publishing script I was using was incorrect, and pulled in too many things as a compile dependency, exposing them transitively despite them being listed as implementation dependencies. I fixed this in later versions.

zsmb13commented, Sep 21, 2021

You can follow the upcoming release here

Got a bunch of other things to include in it too

Read more comments on GitHub >

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