I’m trying to find a way of dealing with GeoJson (...

# serialization

[gaetan]

I’m trying to find a way of dealing with GeoJson (https://tools.ietf.org/html/rfc7946) in a multiplatform way.
The specification indicates that the type of the property coordinates depends on the first property type.
Expamples:

{
  "type": "Point",
  "coordinates": [
    100,
    0
  ]
}

{
  "type": "LineString",
  "coordinates": [
    [
      100,
      0
    ],
    [
      101,
      1
    ]
  ]
}

[sandwwraith]

Unfortunately, current implementation can’t make decisions how to deserialize object depending on a field inside the object

[gaetan]

Thanks for the answer.

[gildor]

Oh, this format is really bad :(

[gildor]

Maybe somehow possible to deserialize to array of dynamics, or to your own class with custom deserializer (kotlinx.serialization support that, as I understand), because I just do not understand how you can map such structure to class, maybe only to some generic Json structure

[gildor]

I mean this problem is not specific for Kotlin serialization, but for any mapping

[gaetan]

I agree with you about the format but it’s a specification so it should be a use case taked in account. It’s possible with jackson: https://github.com/opendatalab-de/geojson-jackson.

[gildor]

Using JsonSubTypes?

[gildor]

It’s still custom parsing, but with help of Jackson

[gildor]

my point that you probably should to write custom adapter for kotlinx.serialization, that handled this case.

[gaetan]

I don’t know if kotlinx.serialization is still a help for the moment. I think i have to do all the work by custom code and then copy data into some data class.

[gildor]

Not sure that this is possible for abstract classes how for Jackson (probably make sense to ask about such feature), but at least you can have custom non-abstract wrapper above GeoJsonObject

[gildor]

Yes, but you can write custom serializer, so you can copy data to any data class
https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/custom_serializers.md

[gaetan]

Maybe I should do it in two times: a first object that is used only for the type field. Then, when I know the type, I can use the right specialized class.

[gildor]

Not sure, but I think using custom serilizers you can even read type and then deserialize only “coordinates” content separately