I'm trying to deserialize a collection, and runnin...

# kotson

[mkporwit]

I'm trying to deserialize a collection, and running into an issue with null. I have the following data class:

data class DocumentMetadata(val documentId: String, val documentType: DocumentType = DocumentType.SKETCH, val owners: MutableSet<String> = mutableSetOf())

and the following string representation:

{
  "documentId": "__healthCheck",
  "documentType": "SKETCH"
}

I'm trying to just do val meta:DocumentMetadata = Gson().fromJson(metaString), but owners comes up as null in the deserialized type, instead of the expected empty set of strings. Is there some setting to get the default data class values for any elements not in the input string, or will I have to do a TypeAdapter for this?

[Fré Dumazy]

Have you tried serializeNulls()?

val gson = GsonBuilder()
    .serializeNulls()
    .create()

[mkporwit]

Yeah, I did. I get the same behavior on deserialization. This is existing data that was serialized before the owners field was added…

[mkporwit]

If I don’t specify the documentType, just a documentId, I also get that as null, so I guess this is not a problem that is unique to collections.

But the bottom line remains the same — if fields are not specified in the string, I would like them to have the data class default values. Can I do that w/o a TypeAdapter?