Hi all! Could someone point me to some best-practices when it comes to using JPA with kotlin? For ex...

# spring

[Sergio Pro]

Hi all!
Could someone point me to some best-practices when it comes to using JPA with kotlin?
For example, in java you don't usually call save() to persist an update of a changed Entity object and simply update the fields. But in kotlin I'd need to use `var`s for that, which seems meh... So how do you do it? Because AFAIK calling save to persist updates is considered a bad practice and forces unnecessary flushes.

[Riccardo Lippolis]

this article gives some good pointers regarding JPA and data classes: https://jpa-buddy.com/blog/best-practices-and-common-pitfalls/

However, in my own personal experience, I would say that if you really dislike `var`s, try to stay away from JPA. Although to some extent in some cases it can work with immutable data classes, it can lead to some nasty bugs in many other cases. So I tend to accept the fact that it works better with `var`s and just keep the usage of these classes contained within the persistence layer.

Regarding the save method in JPA repositories, I recommend this article: https://vladmihalcea.com/best-spring-data-jparepository/

[Sergio Pro]

Thanks a lot for the links, @Riccardo Lippolis.

[Raimund Klein]

The short answer is that JPA entities are mutable by nature. That's why e.g. Java records or classes built using the immutables library don't lend themselves well to entity classes either. They're contradicting concepts. If you want to use JPA, like @Riccardo Lippolis says, accept mutability and limit it to the persistence layer/module.

[Sergio Pro]

Thanks. Yeah, that's apparently "the way". I'm not sure I can avoid JPA (would need to bring some really good arguments to abandon it), so I guess mutable vars it is

[Sergio Pro]

Been playing around with it for a few hours now, and I can see why it needs to be mutable

[Jacob]

JPA is very stateful. Its not really inline with the direction the industry has been going. I would avoid it

[asm0dey]

Starting from this slide: https://asm0dey.github.io/kotlin-spring-springio/25