Custom serializer not annotated on variable declaration for DTO-generated class

[runningjustin]

I have a DTO with the following annotation:

    @Serializable(with = BigDecimalSerializer::class)
    subtotal

This references the subtotal field in my Entity, which is defined like this:

    @Serializable(with = BigDecimalSerializer::class)
    val subtotal: BigDecimal?

When the class gets generated, the variable is declared as private (no annotation), then exposed as public with the annotation.

    private var _subtotal: BigDecimal? = null
    ...
    @property:Serializable(
        with = BigDecimalSerializer::class
    )
    public var subtotal: BigDecimal?
        get() = _subtotal
        set(subtotal) {
            _subtotal = subtotal
        }

This results in the following compiler error:
Serializer has not been found for type 'BigDecimal?'. To use context serializer as fallback, explicitly annotate type or property with @Contextual

Am I annotating in the DTO incorrectly? If not, is this a bug?

[babyfish-ct]

Yes, I remove the annotation of private field and move it to public property.

This behavior affects kotlin serialization. is it?

[runningjustin]

Yeah - gives that compiler error. I can manually add the annotation to the private var and it seems to work.

[babyfish-ct]

I don't know kotlin serialization, can you tell me why this causes compiler error and how does kotlin serialization work?

[babyfish-ct]

If DTO language supports explicit annotation target like kotlin

Input TransactionCreate {
    @field:Serializable(with = BigDecimalSerializer::class)
    subtotal
}

Can it resolve problem? If yes, submit FR please.

[runningjustin]

This doesn't seem to work.

Apparently not even valid syntax if added directly to the generated class.

[babyfish-ct]

Of course, I cannot work because it is a new design which is not implemented yet. I mean if this feature can resolve your problem please add a FR.

However, the @Serializable of kotlin serialization does not support field.

[babyfish-ct]

OK, now the DTO does not use the implicit backing field of kotlin, it uses explicit backing field whose name start with "_".

If this broken kotlin serializaton and there is no workaround, I will change the DTO to remove explicit backing field.

Howevery, I'm super busy now, please wait a few days.

[runningjustin]

Thanks, greatly appreciate it and respect your time. FR submitted: #533

[runningjustin]

I pulled down 0.8.126 this morning and I see that the private variables have gone away (good). But now how can I apply my custom serializer? I tried the various syntaxes discussed above but nothing makes its way onto the DTO...

[babyfish-ct]

    @property:Serializable(
        with = BigDecimalSerializer::class
    )
    public val subtotal: BigDecimal?

Does the annotation move to generated DTO?

[runningjustin]

No, it doesn't. I tested this with 0.8.126 with the syntax above on my Transaction @Entity and it still doesn't affect the generated dto classes.

[babyfish-ct]

It cannot be reproduced, I validate it like this

1. Provide annotation which has the same allowedTargets for kotlinx.serialization.Serializable

2. Use it in DTO language

3. This is the generated DTO

[babyfish-ct]

Oh, you said entity, not DTO.

[babyfish-ct]

Try 0.8.128

[runningjustin]

That did it! Thank you! 🙌