How to Avoid Common Pitfalls With JPA and Kotlin | The IntelliJ IDEA Blog

Kotlin and Jakarta Persistence (JPA) together form a popular combination for server-side development, offering modern language features and a proven persistence framework. However, Jakarta Persistence was originally designed for Java, presenting challenges in aligning Kotlin's features such as null safety and data classes with JPA's specifications. The article outlines best practices for building reliable persistence layers in Kotlin, emphasizing the need for open classes, no-argument constructors, and mutable attributes to meet JPA's requirements. It discusses the limitations of using Kotlin's data classes for JPA entities and recommends using regular open classes to accommodate JPA's needs for proxy creation and lazy loading. It also highlights issues with Kotlin’s null safety and default values in the context of JPA, alongside practical solutions like using plugins to modify Kotlin’s default behaviors. The upcoming IntelliJ IDEA 2026.1 will aid developers by automatically detecting and highlighting potential issues, streamlining the process of integrating Kotlin with JPA.