Hi, I need to (only) deserialize some JSON I do no...

# serialization

[nkiesel]

Hi, I need to (only) deserialize some JSON I do not control:

[ { "item": "first" }, { "item": { "name": "second", "value": 3 }, { "item": "last" } ]

and I thought I could use sealed classes for this. However, this does not work because the item value is sometime not an object but just a string. What is the best approach handling this? Note: I tried to simplify my real data, but that might lead to misleading answers. I reality, these "items" are nested values in some larger JSON:

{
  "id": 3,
  "data": [
    {
      "data": {
        "id": 4,
        "item1": "i1",
        "item2": {
          "k": "k1",
          "v": 1
        }
      }
    },
    {
      "data": {
        "id": 4,
        "item1": {
          "k": "i2",
          "v": 3
        },
        "item2": {
          "k": "k4",
          "v": 1
        }
      }
    }
  ]
}

so really the issue it that items are sometimes strings and sometimes objects.

[Adam S]

one simple solution is to decode to JsonElement and then write some Kotlin code to convert/filter/manipulate the resulting objects

[nkiesel]

Yeah, that's an option. I also saw suggestions to use Any , but I was hoping for some type-safe and declarative approach.

[Adam S]

you can use JsonContentPolymorphicSerializer, which is a slightly more structured way of using JsonObject :)

https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/json.md#content-based-polymorphic-deserialization