Serialize a list of optionals with kotlinx serialization

Question

How can I stringify a list of optional strings with kotlinx serialization? I would like to execute something similar to:

val json = Json(JsonConfiguration.Stable)
val data: List<String?> = listOf("v1", null, "v3")
val dataJson = json.stringify(String.serializer().list, data)

However, this does not compile. I understand that String.serializer().list provides a SerializationStrategy<List<String>> where I need a SerializationStrategy<List<String?>>. How can I acquire the latter?

score 5 · Accepted Answer · answered Aug 27 '19 at 07:42

5

You can use NullableSerializer:

val dataJson = json.stringify(NullableSerializer(String.serializer()).list, data)
println(dataJson) // prints ["v1",null,"v3"]

answered Aug 27 '19 at 07:42

Andrei Tanana

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Exactly what I was looking for, much appreciated! – Roland van der Linden Aug 27 '19 at 08:23

Serialize a list of optionals with kotlinx serialization

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