A modern programming language that makes developers happier.

kotlinlang

Hi folks. What are your best practices to map data classes to other data classes?
For example we have multiple layers in our ktor application (requests/responses, DTOs, entities...) and this is always a lot of boilerplate code to map classes (even with extension functions)
Is there some state of the art for it?

there are quite a few options, such as <https://github.com/mapstruct/mapstruct-examples/tree/main/mapstruct-kotlin>, <https://github.com/krud-dev/shapeshift>, and even <https://kopyk.at/#isomorphic-copy-constructors>

Be careful with using annotations and string-references to achieve this! You loose a lot of refactorability when picking such a solution. The ShapeShift lib allows you to do it w/o these perils, buttt aws you see it is not much shorter than manuall implementing a `toXYZ()`  or `fromXZY()` methods when needed.

i find it easier just to implement mapping extension functions. It's "in your face", honest code, no black magic, easy to refactor if needed. It's boiler-plate-ly, of course,  but if you use something like Copilot, it's usually one Tab press to write