As Spring Boot continues to evolve, developers must stay up-to-date with the latest changes and updates. One of the significant alterations in Spring Boot 3 involves the shift from javax.persistence to jakarta.persistence for handling annotations related to entities, IDs, and generated values. In this article, we will explore this migration process and address a common issue that may arise during the transition.

In Spring Boot 2, when working with MySQL or other databases, you may have frequently used annotations provided by javax.persistence.*, such as @Entity, @Id, and @GeneratedValue. However, Spring Boot 3 has made a crucial change - it replaces javax.persistence with jakarta.persistence. As a result, in Spring Boot 3, you need to import annotations from jakarta.persistence instead of javax.persistence.

When migrating to Spring Boot 3, many developers encounter a perplexing error that is not easily resolved by simply adding a Maven dependency:

ERROR 22196 — — [ main] o.s.boot.SpringApplication : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myRepo' defined in com.mysqltest.mysqltest.MyRepo defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration:

Not a managed type: class com.mysqltest.mysqltest.MyEntity

Error:Not a managed type: class com.mysqltest.mysqltest.MyEntity

This error often leaves developers scratching their heads and scouring the internet for solutions. The common recommendation is to verify the annotations, but this may not always lead to a resolution.

The root of this problem lies in the migration from javax.persistence to jakarta.persistence. While it's tempting to believe that adding the javax.persistence-api dependency with a version like 2.2 would fix the issue, this approach is not sufficient in Spring Boot 3.

To resolve this issue, developers must explicitly update their codebase to use the jakarta.persistence annotations. Here's how you can make the necessary changes:

1. Update Imports:
   In your Java classes, replace all javax.persistence imports with jakarta.persistence. This includes replacing @Entity, @Id, @GeneratedValue, and any other annotations related to persistence.
2. Dependency Management:
   Ensure that your project’s build tool (Maven or Gradle) uses the latest versions of libraries that are compatible with Spring Boot 3. Specifically, make sure you are using jakarta.persistence dependencies instead of javax.persistence.
3. Check External Libraries:
   If your project relies on external libraries that use javax.persistence, consider updating or replacing them with versions that are compatible with Spring Boot 3.
4. Testing:
   Thoroughly test your application to ensure that all changes have been correctly implemented. Pay special attention to database operations and entity management.
   Here’s the Sample Updated Entity Class:

package com.mysqltest.mysqltest;

import jakarta.persistence.Entity;

import jakarta.persistence.GeneratedValue;

import jakarta.persistence.Id;

import lombok.Data;

@Data

@Entity

public class MyEntity {

    @Id

    @GeneratedValue

    private Long id;

    private String name;

    private int runs;

    private int wickets;

    private String team;

    private String iplTeam;

}

In this updated entity class:

• We have removed the previous javax.persistence imports and replaced them with the corresponding jakarta.persistence imports.
• Annotations such as @Entity, @Id, and @GeneratedValue have been updated to their jakarta.persistence equivalents.

By making these changes, you ensure that your entity class is compatible with Spring Boot 3, and it will work seamlessly with the new version of the framework. This is a crucial step in the migration process, as it allows your application to continue working as expected while benefiting from the latest Spring Boot features and improvements.

Migrating from Spring Boot 2 to Spring Boot 3 may come with its challenges, especially when dealing with the transition from javax.persistence to jakarta.persistence. By following the solutions mentioned in this blog, you can successfully update your codebase and ensure compatibility with Spring Boot 3. Stay up-to-date with the latest changes and updates in order to leverage the new features and improvements offered by Spring Boot.