Hi all, I have question regarding annotations. Assume a following example

open class A(val strings: List<String>)

class B(strings: List<String>) : A(strings)

class C(strings: List<String>) : A(strings)

these classes are used in my REST API and I would like to validate their content with JSR annotations. I want to check that the collection

strings

in class

B

is not empty using

@NotEmpty

but I can apply this validation only on the property declaration (if I’m not mistaken). What is the best Kotlin way to add this validation to class

B

? In java I would probably override getter in class B and add annotation there, can I do something similar in Kotlin?

Sorry not to answer your question, but looking back my non-trivial Kotlin project using JSR annotations I would not use them at all. I think Kotlin provides far better options in this area

No problem with not answering the question. We are using JSR quite some time and it is not feasible to change it… I’m just new to kotlin and I do not know how to handle this problem in kotlin idiomatic way.

you can change

class B(strings: List<String>) : A(strings)

to

class B(@get:NotEmpty override val strings: List<String>) : A(strings)

I have tough that this the way how to solve the problem, but somehow I do not like to override the property to just have this annotation.

Sorry for interrupting the thread, but @Jukka Siivonen can you please elaborate more why don’t like JSR annotations with kotlin?

Mostly because I think validation should not be hardcoded in types and also like I said "external" validation with Kotlin should be very clean, for example https://www.konform.io/

Thanks a lot for the explanation

jsr is not the best api I ever saw, but it is actually super-convenient once you really know how it works. While I would like more a dsl api rather than an annotation api, being a standard it means it integrates awesomely with a lot of tooling to help with the non-functional requirement of validation. for instance, hibernate-validator recently added a feature to automatically transform the error path, so if you are receive a json request and validating the request, you can easily return a response where you indicate the json name of the field violating the rules, rather than the kotlin/java you would get natively