api/co.anitrend.retrofit.graphql.model/GraphQLData

GraphQLData

sealed interface GraphQLData<out T>(source)

Backend-neutral presence model for the data entry of a GraphQL response.

GraphQLData distinguishes three wire states that a plain nullable field would conflate:

Absent: the response contains no data entry at all.
Present with a non-null value: the response contains data with a value.
Present with a null value: the response contains data: null.

Usage

fun describe(data: GraphQLData<Viewer>) {
    when (data) {
        is GraphQLData.Absent -> println("no data entry")
        is GraphQLData.Present -> {
            val value: Viewer? = data.value
            println(if (value == null) "data: null" else "data present")
        }
    }
}