Data Class Validations not working in Micronaut

Question

Context: I'm using micronaut version 3.4.2 and Kotlin 1.7.22. I have a Data class in another project which I download as a dependency Jar. The javax field validations are not working in the controller layer.

My data Class:

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
data class ItemsTO(
    @field:Min(value = 1, message = "Minimum quantity has to be 1") val quantity: Int
)

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
data class RequestTO(
    val items: List<ItemsTO>
)

My Controller:

@Post("/")
@Status(HttpStatus.CREATED)
fun handleRequest(@Valid @Body requestTO: RequestTO): ResponseTO {}

Reading the documentation I saw that @Introspected is required. I added that annotation as well as @Validated on the controller but it's still doesn't validate the request body; the request goes through. I saw in some other projects where this is implemented and they don't use @Introspected or @Validated annotations.

In the project having the controller(where the data class containing module is imported) I have these in my build.gradle

implementation "io.micronaut:micronaut-validation"
kapt "io.micronaut:micronaut-inject-java"
kapt "io.micronaut:micronaut-validation"

I'm not able to figure out what the issue is and why the fields in the request body are not being validated

Answer 1

Found the issue. In my code I have two data classes. The validation message I'm expecting is from the data class{ItemsTO) used as a type in another data class(RequestTO) field items. Now the request body will be of type RequestTO hence for the validation on ItemsTO to work we need the request body class to be:

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
data class RequestTO(
    @field:@Valid val items: List<ItemsTO>
)

We have to add @field:@Valid on the field whose data class is getting validated.

ref: https://www.baeldung.com/kotlin/valid-spring-annotation#4-validating-nested-objects