Getting “Unable to resolve persistence unit” error when building jar without IDE

Are you facing a Hibernate auto-configuration bug in Spring Boot 1.4 versions that wasn’t present in earlier versions like 1.3.x? This issue, which was silently overlooked, can be resolved through a workaround that disables Spring Boot’s auto-configuration of Hibernate. In this guide, we’ll walk through the steps to implement this workaround effectively.

Understanding the Issue

Spring Boot’s auto-configuration feature aims to simplify the setup and configuration of applications. However, in certain cases, such as the transition from Spring Boot 1.3 to 1.4, this feature can introduce unexpected bugs related to Hibernate auto-configuration. One common symptom is the presence of errors or unexpected behavior in applications that were working fine in earlier versions.

Workaround: Disabling Hibernate Auto-Configuration

To address the Hibernate auto-configuration issue in Spring Boot 1.4, follow these steps:

1. Add Annotation to Application Class:
   In your application’s main class (often annotated with @SpringBootApplication), add the following annotation to exclude Hibernate auto-configuration:

   @EnableAutoConfiguration(exclude = HibernateJpaAutoConfiguration.class)

This annotation tells Spring Boot to skip auto-configuration for Hibernate’s JPA support.

2. Configure Application Properties:
   Include the following property in your application.properties or application.yml file to disable Spring Data JPA repositories:

   spring.data.jpa.repositories.enabled=false

This property prevents Spring Boot from automatically configuring JPA repositories, which can help resolve compatibility issues with Hibernate.

Implementation Example

Let’s see an example of how to apply these changes in a Spring Boot application:

1. Add Annotation to Application Class:

   import org.springframework.boot.SpringApplication;
   import org.springframework.boot.autoconfigure.SpringBootApplication;
   import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
   import org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration;

   @SpringBootApplication
   @EnableAutoConfiguration(exclude = HibernateJpaAutoConfiguration.class)
   public class MySpringBootApplication {
       public static void main(String[] args) {
           SpringApplication.run(MySpringBootApplication.class, args);
       }
   }

In this example, we’ve added @EnableAutoConfiguration with exclusion of HibernateJpaAutoConfiguration.

2. Configure Application Properties:
   Add the property to your application.properties or application.yml file:

   spring.data.jpa.repositories.enabled=false

Benefits of the Workaround

Implementing this workaround offers several benefits:

• Compatibility: Ensures compatibility with Hibernate in Spring Boot 1.4 versions without encountering auto-configuration issues.
• Stability: Prevents unexpected errors or behaviors caused by Hibernate auto-configuration conflicts.
• Control: Allows you to have more control over the configuration of Hibernate and JPA in your Spring Boot application.

Conclusion

By following the steps outlined in this guide, you can effectively resolve the Hibernate auto-configuration issue in Spring Boot 1.4 versions. This workaround provides a reliable solution to ensure smooth operation and compatibility for your Spring Boot applications using Hibernate and JPA.

Citations:

[1] https://www.baeldung.com/the-persistence-layer-with-spring-and-jpa

[2] https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.0-Migration-Guide

[3] https://mkyong.com/spring-boot/spring-boot-package-javax-persistence-does-not-exist/

[4] https://stackoverflow.com/questions/47957197/eclipse-cant-find-javax-persistence-entity-even-though-jar-is-present/49663373

[5] https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-1.4-Release-Notes