Real-world! Developing a library management application with Kotlin and Spring Boot (Refactoring a Java project)

Hello! I have some additional considerations when using Kotlin and JPA together.

The content is that you need to add the following script to build.gradle!

 

plugins { id "org.jetbrains.kotlin.plugin.allopen" version "1.6.21" } // plugins, dependencies와 같은 Level (즉 build.gradle 최상단) allOpen { annotation("javax.persistence.Entity") annotation("javax.persistence.MappedSuperclass") annotation("javax.persistence.Embeddable") }

 

Here's why!

As you know, Kotlin basically makes both classes and functions final!! (That is, it prevents inheritance and overriding!)

However, to fully utilize Proxy Lazy Fetching when using JPA (there's a talk about Lazy Fetching in Lesson 27!), the class must be inheritable!! From what I've checked, Lazy Fetching works for @OneToMany, but it doesn't work for @ManyToOne even if I explicitly give it the Lazy Fetching option.

 

So, through the all-open feature, @Entity classes need to be processed so that the class remains open even when decompiled, and the script above performs that role.

In this lecture, we do not use @ManyToOne Lazy Fetching, so the plugin was not mentioned in the lecture. From now on, I will design more carefully so that I do not miss more content. 🙇 I think it would be good to set up the plugin in the actual project!! Thank you!! 🙏

 

 

(The same content was also uploaded to <Lecture 14. 3 Things to Talk About When Using Kotlin and JPA Together>!)