the `BadRequestException` from Ktor just gives me “Illegal Input” and doesn’t actually say whats wro...

# ktor

[João Gabriel Zó]

the BadRequestException from Ktor just gives me “Illegal Input” and doesn’t actually say whats wrong with the request. Is there a way to improve it?

[simon.vergauwen]

The cause references the original exception from KotlinX Serialization, and that should give you more information.

https://github.com/ktorio/ktor/blob/d7d244cf9f1a8f91675a161b5b97f5ad9681c594/ktor-[…]/io/ktor/serialization/kotlinx/KotlinxSerializationConverter.kt

[simon.vergauwen]

I'm not sure how the JsonException gets turned into BadRequest 🤔

[João Gabriel Zó]

Oh, the problem was me then. I was returning the cause but forgot to log it.
Sorry and thanks!

[João Gabriel Zó]

One last question, do you know if I can return the errors as list in this case?

[simon.vergauwen]

Sadly I think KotlinX Serialization only returns a string of the first value it encounters that is not correct.

You can also manually work with raw Json, and combining it with Arrow to do validation.

This DSL makes it easy to work, and inspect raw JsonElement. https://github.com/nomisRev/kotlinx-serialization-jsonpath

[simon.vergauwen]

I take a similar approach when I need to validate query or path parameters and want to get a complete list of the errors.

[sindrenm]

I just filed an issue on this on YouTrack, as the Logging plugin is essentially unable to display a proper deserialization error message.

https://youtrack.jetbrains.com/issue/KTOR-5421