Am I right that `@Polymorphic` doesn't work with g...

# serialization

[thevery]

Am I right that @Polymorphic doesn't work with generics well?

class ParserTest {
    open class Field

    @Serializable data class FieldB(val a: String, val b: Int) : Field()

    @Serializable data class FieldC(val a: String, val b: Int) : Field()

    @Serializable data class Data(@Polymorphic val a: List<Field>)

    @Test
    fun testPoly() {
        val obj = JSON.parse<Data>("""{"a":[{a:"a", b: 1}]}""")
        println("obj = ${obj}")
    }
}

produces
java.lang.IllegalArgumentException: JSON at 6: Expected '[, kind: kotlinx.serialization.UnionKind$POLYMORPHIC@33e5ccce'

[sandwwraith]

There’s no type information provided in your input. It is recorded in form [“fqClassName”, class_body], so input should look like """{"a":[["FieldC", {a:"a", b: 1}]]}"""

[sandwwraith]

Also, I believe definition should be val a: List<@Polymorphic Field>, but it doesn’t matter for now

[thevery]

ic, thank you. Is there any simple way to provide such info without writing full serializer? I need to distinguish
{"a":[{a:"a", b: 1}]} and
{"a":[{a:"a", c: "1"}]}

[sandwwraith]

I’m afraid not, you need to peek in data before making decision, and this is not what abstract codegen mechanism can do