sealed class support

[Globegitter]

Hey, thanks for this project, so far it looks great but I am running into some limitations with sealed classes. I have a model as follows:

data class Tablet(
    val id: String,
    val something: Something,
    val apps: Map<String, App>
)

where-as app is a sealed class and while jackson 2.10.1 recognises that and converts incoming requests perfectly fine in the generated json schema App is only displayed as an empty object. Are sealed classes meant to be supported? As far as I can tell that would probably map to a oneof, right?

Edit: For reference, here is btw the PR that added auto-discovery of sealed classes: FasterXML/jackson-module-kotlin#240

[Wicpar]

indeed you should have a warning in the log "No public properties found in object $type"
i can try and add sealed class support right now.

[Globegitter]

@Wicpar Ah yeah, that would be great indeed. I gave it a quick try by adding to SimpleSchemaRegistrar.kt:

private fun SchemaRegistrar.makeSealedSchema(type: KType) = type.jvmErasure.sealedSubclasses
        .let { props ->
            props
                .filter { it.visibility == KVisibility.PUBLIC }
                .associate {
                    Pair(it.java.name, get(it.java.toKType()).schema)
                }
                .let { properties ->
                    if (properties.isEmpty()) log.warn("No public properties found in object $type")
                    Schema.SchemaObj<Any>(
                        properties,
                        props.filter { !it.java.toKType().isMarkedNullable }.map { it.java.name })
                }
        }

and it does now show the classes in the swagger UI. But this was a complete blind stab, so not sure if that makes complete sense and also not sure if that is the best way to display it in the UI. So if you could take a look that would be really appreciated.

[Wicpar]

@Globegitter
since sealed classes are a special case for objects, the implementation would actually be replacing:

    private fun SchemaRegistrar.makeObjectSchema(type: KType): Schema<*> {
        val erasure = type.jvmErasure
        if (erasure.isSealed) {
            return Schema.OneSchemaOf(erasure.sealedSubclasses.map { get(it.starProjectedType).schema })
        }
        val props = erasure.declaredMemberProperties.filter { it.visibility == KVisibility.PUBLIC }
        val properties = props.associate {
            Pair(it.name, get(it.returnType).schema)
        }
        if (properties.isEmpty()) log.warn("No public properties found in object $type")
        return Schema.SchemaObj<Any>(
            properties,
            props.filter { !it.returnType.isMarkedNullable }.map { it.name })
    }

it works with the description, but jackson is not able to parse it properly through call.receive

This implementation supports circular definitions in the model.

[Globegitter]

Ah yeah, that is already looking much better - thanks. I am not sure I fully understand the comment but jackson is not able to parse it properly through call.receive though.

[Wicpar]

Do you simply send object based on a subclass or also want to receive them?
Sending works fine, but receiving throws a jackson exception.

[Globegitter]

I do want to receive them, i.e. this is the request json for a post endpoint. But I have tried this change and at least in my unit test it is working fine with sending the json as a string and me receiving it as the correct object.

[Wicpar]

In my tests:

...
                route("sealed") {
                    post<Unit, Base, Base>(
                            info("Sealed class Endpoint", "This is a Sealed class Endpoint"),
                            exampleRequest = Base.A("Hi"),
                            exampleResponse = Base.A("Hi")
                    ) { params, base ->
                        respond(base)
                    }
                }
...

    sealed class Base {
        data class A(val str: String) : Base()
        data class B(val i: Int) : Base()
        data class C(val l: Long) : Base()
    }

does not work when receiving a json request body that is A, B, or C.

[Globegitter]

You would have to add e.g.:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME)
sealed class Base {
        data class A(val str: String) : Base()
        data class B(val i: Int) : Base()
        data class C(val l: Long) : Base()
}

and then make sure the json contains an extra @type field with the name of the class, so e.g. A

And make sure to use jackson 2.10.1

[Wicpar]

i got it to work with:

    @JsonTypeInfo(use = JsonTypeInfo.Id.NAME)
    @JsonSubTypes(
            JsonSubTypes.Type(Base.A::class, name = "a"),
            JsonSubTypes.Type(Base.B::class, name = "b"),
            JsonSubTypes.Type(Base.C::class, name = "c")
    )
    sealed class Base {
        class A(val str: String) : Base()
        class B(val i: Int) : Base()
        class C(val l: Long) : Base()
    }

[Wicpar]

i have pushed the modifications.
c2b7932