Make a field optional in Kotlinx serialization

Question

Here is my pojo class

@Serializable
data class Response(
    @SerialName("message") val message: String?,
    @SerialName("parameters") val parameters: Map?
)

And this is Json, I was trying to decode from:

{
   "message": "Some text"
}

Here, the field parameters is optional. When I try to decode like

Json.decodeFromString(response)

I am getting the following exception:

kotlinx.serialization.MissingFieldException: Field 'parameters' is required for type with serial name 'Response', but it was missing

I was looking forward to set the field parameters to null, if the field is missing in the Json

user_448875 · Answer

You need to specify a default value for your parameters property like this:

@Serializable
data class Response(
    @SerialName("message") val message: String?,
    @SerialName("parameters") val parameters: Map? = null
)