How to Avoid Common Pitfalls With JPA and Kotlin

• Avoid null-safety conflicts by using nullable types carefully in entity fields. • Ensure entity classes have a public no-argument constructor for JPA hydration. • Do not declare entity attributes as final; JPA needs to set them post-construction. • Leverage IntelliJ IDEA 2026.1 inspections to catch common JPA/Kotlin mismatches early. • Prefer data classes for DTOs, not entities, to avoid unintended immutability. • Use @Entity annotations with proper mapping; avoid Kotlin-specific features that break spec.

Article Summaries:

• IntelliJ IDEA 2026.1 introduces new inspections that automatically flag common issues when using Jakarta Persistence (JPA) with Kotlin. The article, co‑authored by JPA veteran Thorben Janssen, outlines best practices for building reliable persistence layers in Kotlin. It explains that JPA entity classes must have a no‑argument constructor, non‑final attributes, and non‑final classes to support reflection, hydration, and proxy creation. The piece also advises careful implementation of equals, hashCode, and toString, and distinguishes Kotlin data classes-ideal for DTOs-from entity classes. These guidelines help developers avoid mismatches between Kotlin’s language features and JPA’s specifications.

Sources:

• https://blog.jetbrains.com/idea/2026/01/how-to-avoid-common-pitfalls-with-jpa-and-kotlin/