How can I write my custom serializer to achieve t...

# serialization

[Endre Deak]

How can I write my custom serializer to achieve the following?

@Serializable
data class Foo(val name: String, val bar: Bar)

@Serializable
sealed class Bar
data class Bar1(val x: String) : Bar
data class Bar2(val y: Int): Bar

val foo1 = Foo("myFoo1", Bar1("Bar1"))
val foo2 = Foo("myFoo2", Bar2(2))

as JSON it should be

"myFoo1": { "type": "bar1", "x": "Bar1" }
"myFoo2": { "type": "bar2", "y": 2 }

[jw]

You don't need one

[jw]

Slap @SerialName("bar1") on Bar and @SerialName("bar2" on Bar2 and you're done

[jw]

oh do you mean for Foo?

[jw]

you can't quite make that exact transformation because names belong to the parent object. what does a type like

@Serializable
class Enclosing(
  val one: Foo,
  val two: Foo,
)

serialize as?

[Endre Deak]

for the context, I'm trying to make wrappers around this API: https://microsoft.github.io/presidio/api-docs/api-docs.html#tag/Anonymizer/paths/~1anonymize/post

[Endre Deak]

and the list of anonymizers is the question - if possible, I'd avoid creating a separate type for every single field, but it might be the case that I'd have to

[Endre Deak]

or, I just pick a different serializer lib like GSON where it's possible.

[jw]

Looks like pretty standard polymorphism https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/polymorphism.md

[Endre Deak]

not sure how... there are multiple dynamic structure names (e.g. PERSON and PHONE_NUMBER, and there are multiple field sets that could go into that structure.

for example:

"anonymizers": {
    "PERSON": {
        "type": "redact"
    },
    "PHONE_NUMBER": {
        "type": "replace",
        "new_value": "ANONYMIZED"
    }
}

I'm not sure how this could be created dynamically

[jw]

I see. For that I'd do a List<Anonymizer> and a custom serializer for the anonymizers property which converted the list into the map. This goes back to what I was saying about the parent object owning the name, the anonymizers serializer creates the parent object and thus can write names based on the child elements.

[Endre Deak]

ahh I haven't realized that it's actually a map

[Endre Deak]

🤦‍♂️

[jw]

i have to run so if you have any other questions or more specific questions about how to do it hopefully someone else can chime in

[Endre Deak]

I think I got it from here

[Endre Deak]

🙏

[Endre Deak]

fwiw the final structure looks like this:

@Serializable
data class Request(
    val anonymizers: Map<String, AnonymizerType>? = null
)

@Serializable
sealed class AnonymizerType

@Serializable
@SerialName("replace")
data class Replace(
    @SerialName("new_value") val newValue: String
) : AnonymizerType()

@Serializable
@SerialName("redact")
object Redact : AnonymizerType()

// ...