How to invoke default deserialize with gson

Question

I get a json that has \"field\" field.
If the \"field\" has data, then there is an OBJECT that has many (about 20) other fields that are also objects. I can deserialize

Answer 1

I created an alternative TypeAdapter based on my needs to let empty arrays deserialize to null, but only for the classes I specify:

class EmptyArraysAsNullTypeAdapterFactory @Inject constructor() : TypeAdapterFactory {

companion object {

    // Add classes here as needed
    private val classesAllowedEmptyArrayAsNull = arrayOf(Location::class.java,
                                                         Results::class.java)

    private fun isAllowedClass(rawType: Class<*>): Boolean {
        return classesAllowedEmptyArrayAsNull.find { rawType.isAssignableFrom(it) } != null
    }
}

override fun  create(gson: Gson, type: TypeToken): TypeAdapter? {
    val delegate = gson.getDelegateAdapter(this, type)

    val rawType = type.rawType as Class

    return object : TypeAdapter() {

        override fun write(out: JsonWriter, value: T?) {
            delegate.write(out, value)
        }

        override fun read(reader: JsonReader): T? {
            return if (reader.peek() === JsonToken.BEGIN_ARRAY && isAllowedClass(rawType)) {
                reader.beginArray()

                // If the array is empty, assume it is signifying null
                if (!reader.hasNext()) {
                    reader.endArray()
                    null
                } else {
                    throw JsonParseException("Not expecting a non-empty array when deserializing: ${type.rawType.name}")
                }

            } else {
                delegate.read(reader)
            }
        }
    }
}

}