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kotlinlang

If I have a custom
```JsonTransformingSerializer&lt;String&gt;(String.serializer())```
How can I add this to a json format, serializer module or whatever so it applies to all `String` in the serialized type ? ie. I want to transform all strings

which property serializers are used by a class's serializer is determined when it is built (except in the case of `@Contextual` or polymorphic, in which case it retrieves the serializer from the serializersModule)

tl;dr you can't do it for all strings in a format, you have to use `@Serializable(with = ...) String` at all the use sites

Is there any other hook then where I can transform all strings then ? I have browsed most of the json code but everything seems internal. (ie. JsonEncoder, JsonWriter etc.)

not easily. a custom format that changes `decodeString` could, but that would break things like polymorphic type discriminators

For reasons I need to transform multibyte characters to their "escape" sequence ie. Curaçao -&gt; Cura\u00e7ao

ah, you could do that as a post-processing step

You mean in-place replacement in the serialized json bytes ?

yeah, if you're just replacing non-ASCII characters with escaped variants, you can just do that on the String

it won't change anything about the JSON structure

you could file a feature request for this to be a feature in the JSON format, but I don't think it's a common need

Yeah it could work. A bit out of the box and I will have to switch away from the streaming encoder.

maybe try a value class.

```@JvmInline
@Serializable(with = MultibyteStringSerializer::class)
value class MultibyteString(val value: String): CharSequence by value

object MultibyteStringSerializer : KSerializer&lt;MultibyteString&gt; {
   // encode/decode...
}```
then you can use MultibyteString instead of String in your DTOs

that doesn't really help though. you don't have a way of writing that serializer to produce the desired output

if it performs escaping, the Json format will escape those escapes, resulting in `\\` in the output

oh I didn’t realise that was the case. Outputting that sort of raw string should be possible in KxS 1.5, with JsonUnquotedLiteral