Support @AvroDefault(value=null)

[fugithub79]

I want to generate a schema file. Given fields like the following

    @AvroDoc("For coupons only.  If the reward is a coupon, this will be the id")
    val coupon_id:Int? = null,

    @AvroDoc("For coupons only.  The start date of the coupon.")
    @Serializable(with= InstantSerializer::class)
    val coupon_timestamp:Instant? = null,

    @AvroDoc("For coupons only.  The date when the coupon should first be displayed to the user.")
    @Serializable(with= InstantSerializer::class)
    val coupon_display_timestamp:Instant? = null,

I would like to add "default": null to each of these in the generated schema. Unfortunately, it appears that I can't do something like:

    ...
    @Serializable(with= InstantSerializer::class)
   @AvroDoc(value=null)
    val coupon_display_timestamp:Instant? = null

Because the parser considers this to be invalid.

Is this an actual issue? Short of writing my own serializer, is there another way to accomplish the same thing?

[kossi]

Hi @fugithub79

I don't know if this is an actual issue or should this be actually supported but have you tried to use the @AvroDefault annotation? Or on my current project this works or a "generator" does something like this ->

@AvroDefault(Avro.NULL)
val maybe: Sting? = null

[thake]

Should work as @kossi has written. Closing this issue.

[samu-developments]

I tried to get the "default": null in my schema, however it seems like I'm missing something?

@Serializable
data class Test(
    @AvroDefault(Avro.NULL)
    val nullable: String? = null
)

val record = Avro.default.schema(
    serializer = Test.serializer()
)
println(record)

yields {"type":"record","name":"Test","namespace":"com.test.avro","fields":[{"name":"nullable","type":["null","string"]}]}

How can I get

{"type":"record","name":"Test","namespace":"com.test.avro","fields":[{"name":"nullable","type":["null","string"], "default": null}]}

I use avro4k with AWS MSK+Glue schema registry with auto registration of new schemas, and schema compatibility fails since Glue complains about new nullable fields without a default value.

Thanks

edit. Wrong AvroDefault import :facepalm: