Hi. I'm a Kotlin newbie and interested in hearing is it possible to have an utility to deep-merge tw...

# announcements

[Tommi Reiman]

Hi. I'm a Kotlin newbie and interested in hearing is it possible to have an utility to deep-merge two data class instances of same type? Failed on inline + recursion...

[Tommi Reiman]

wrote it stackoverflow while waiting to get in here: https://stackoverflow.com/questions/59950612/deep-merging-data-classes-in-kotlin

[Czar]

I don't think you need reification here, so you can get rid of inline.

fun <T : Any> T.merge(other: T): T {
  val nameToProperty = this::class.declaredMemberProperties.associateBy { it.name }
//...

[Czar]

I've posted full answer to SO

[Tommi Reiman]

Big thanks!! Will answer to SO. There was a small thing with deeply nested data classes, but works like a charm.

[Czar]

Yeah, indeed it was 🙂 Missed the bugger, fixed now: return rightValue?.let { leftValue?.merge(it) } ?: rightValue ?: leftValue

[Tommi Reiman]

Hi. Back in trouble. Wanted to add support for merging nested `Map`s. As the type information is lost, can’t figure out how to make it work. Here’s the problem statement: https://gist.github.com/ikitommi/c5e32bf1c3901b3ddf9f5fb6289c414e with a sample deepMerge, which doesn’t comple.

[Tommi Reiman]

Jackson Kotlin module works, it uses erasedType(), but coudn’t figure out how to use that here. Anyway, here’s the code for it: https://github.com/FasterXML/jackson-module-kotlin/blob/master/src/main/kotlin/com/fasterxml/jackson/module/kotlin/Types.kt

[Tommi Reiman]

Any help would be appreciated.

[Czar]

Sorry, mate, no time. Try posting this as a separate question mentioning only merging maps.

[Tommi Reiman]

ok, thanks!