Provide way to encode unquoted String in JSON format

[sandwwraith]

Mainly to write big numbers. See reasoning here: #1051 (comment)

[JakeWharton]

Another use case is embedding known JSON documents into others without having to go through an intermediate parsing step. As long as it's named sufficiently scary this can be a powerful escape hatch.

[nikolaykasyanov]

Should this issue also include support for decoding JSON primitives as raw strings (to be able to convert them to smth like mentioned BigDecimal)?

[Kantis]

Do you see any downsides to this approach? I suppose it might be prone to breaking, but it seems to work at least. Obviously it should only be used when working with json as serial format.

⚠️ See DrMetallius' comment below, this only works when deserializing. When serializing, the underlying implementation will still parse the string into a Double

object BigDecimalSerializer : KSerializer<BigDecimal> {

    override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("BigDecimal", PrimitiveKind.STRING)

    override fun deserialize(decoder: Decoder): BigDecimal =
        (decoder as JsonDecoder).decodeJsonElement().jsonPrimitive.content.toBigDecimal()


    override fun serialize(encoder: Encoder, value: BigDecimal) {
        (encoder as JsonEncoder).encodeJsonElement(JsonPrimitive(JsonBigDecimal(value)))
    }
  
    private class JsonBigDecimal(value: BigDecimal) : Number() {
    
        private val serialized: String = value.toString()
    
        override fun toString() = serialized
    
        override fun toByte() = notSupported()
        override fun toChar() = notSupported()
        override fun toDouble() = notSupported()
        override fun toFloat() = notSupported()
        override fun toInt() = notSupported()
        override fun toLong() = notSupported()
        override fun toShort() = notSupported()
    
        private fun notSupported(): Nothing = throw IllegalStateException("This method should not be invoked, ever.")
    }
}

[nikolaykasyanov]

@Kantis thanks for sharing, seems to be working great!

[DrMetallius]

This solution unfortunately only works only for decoding. When encoding, the value will get converted to double by JsonLiteralSerializer.

[Kantis]

This solution unfortunately only works only for decoding. When encoding, the value will get converted to double by JsonLiteralSerializer.

Darn. I accidentally asserted my expected too precise for double number through a JSON parser which ended up doing the same double-conversion.

Added a warning to my original comment and code snippet.

[nikolaykasyanov]

Thanks for sharing @DrMetallius, good to know the limitations.

@sandwwraith looks like there's no viable workaround for serialization, would it be possible to proiritize the issue?

[sandwwraith]

I think we'll include this in plans for the next release

[nikolaykasyanov]

@sandwwraith that's great to hear, thank you 🙏

[vivekmalhotragithub]

any updates on this issue?

[nikolaykasyanov]

@sandwwraith 👋 hello, I wonder if this is still planned.

[aSemy]

@nikolaykasyanov encoding raw strings to JSON was completed in #2041, and it will be available in a month or two.