Default values for optional fields serialized even when encodeDefaults set to false

[sav007]

After upgrading to the latest version 0.11.0 @Optional annotation is deprecated.

The doc says:

All properties with default values are considered optional now

But it seems that without this annotation the flag encodeDefaults=false in JsonConfiguration is ignored for optionals fields without deprecated @Optional annotation, and default values (such as null for instance) serialized to the result json.

[sandwwraith]

Can you post more details about the problem, please (code sample, platform, versions, ...)? I can't reproduce it.

[sav007]

Sure, here is the sample:

val json = Json(
            JsonConfiguration(
                encodeDefaults = false,
                strictMode = false
            )
        ).stringify(
            AppliedDiscount.serializer(), AppliedDiscount(
                amount = "0.00",
                title = null,
                description = "Description"
            )
        )

For AppliedDiscount with deprecate @Optional annotation:

@Serializable
internal data class AppliedDiscount(
    val amount: String,
    @Optional
    val title: String? = null,
    val description: String
)

The emitted json string will be:

{"amount":"0.00","description":"Description"}

For AppliedDiscount without @Optional:

@Serializable
internal data class AppliedDiscount(
    val amount: String,
    val title: String? = null,
    val description: String
)

The output will be:

{"amount":"0.00","title":null,"description":"Description"}

[sandwwraith]

Which version of Kotlin compiler do you use? Make sure it is 1.3.30. Previous versions, indeed, still need the annotation.

[sav007]

Agh, I see. Yeah I was using 1.3.21, so it depends on the version of kotlin compiler TIL. Thanks!

[marlonlom]

how can i handle optional fields from json using retrofit, since @optional is deprecated?

[pdvrieze]

@marlonlom There is an opposite annotation: @Required that is able to specify that a type must be present even if it is optional due to having a default value.

[sandwwraith]

@marlonlom all Kotlin properties with default values are automatically optional now

[marlonlom]

@sandwwraith great! :)