Multi-type items

[DanySK]

Hi,
I'd like to be able to express the following valid configurations:

multitype: somestring

multitype:
  a: map

I can support either one, but not both:

object FooSpec : ConfigSpec("") {
    val multitype by required<String>() // former case
}

object FooSpec : ConfigSpec("") {
    val multitype by required<Map<String, String>>() // latter case
}

Is there a way to capture both cases? I cannot rename the key.

[DanySK]

I tried this strategy:

class MapOrString private constructor(source: Either<String, Map<String, String>) {
    val string: String? = source.leftOrNull
    val map: Map<String, String>? = source.rightOrNull

    constructor(stringDescriptor: String) : this(Either.left(stringDescriptor))
    constructor(map: Map<String, String>) : this(Either.right(map))
}
object FooSpec : ConfigSpec("") {
    val multitype by required<MapOrString>()
}

but it fails with:

Exception in thread "main" com.uchuhimo.konf.source.LoadException: fail to load multitype
	at com.uchuhimo.konf.source.SourceKt.loadItem(Source.kt:638)
	at com.uchuhimo.konf.source.SourceKt$load$1.invoke(Source.kt:653)
	at com.uchuhimo.konf.source.SourceKt$load$1.invoke(Source.kt)
	at com.uchuhimo.konf.BaseConfig.lock(BaseConfig.kt:66)
	at com.uchuhimo.konf.source.SourceKt.load(Source.kt:651)
	at com.uchuhimo.konf.BaseConfig.withSource(BaseConfig.kt:608)
	at com.uchuhimo.konf.source.Loader.string(Loader.kt:204)
        ...
Caused by: com.uchuhimo.konf.source.ObjectMappingException: unable to map source somestring in [type: YAML, content: "
multitype: somestring
"] to value of type MapOrString
	at com.uchuhimo.konf.source.SourceKt.toValue(Source.kt:952)
	at com.uchuhimo.konf.source.SourceKt.loadItem(Source.kt:631)
	... 8 more
Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `arrow.core.Either` (no Creators, like default constructor, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
 at [Source: UNKNOWN; line: -1, column: -1]

It looks like Konf never tries secondary constructors...

[DanySK]

I found a way! Secondary constructors need to be annotated with @JsonCreator!
This should really be documented...

[stale]

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