Resolving PersistentObjectException in Spring Boot: A Guide to Error Fixing

Encountering a `PersistentObjectException` in your Spring Boot application when adding new sales? Learn how to debug and fix this error efficiently with our in-depth guide.
---

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Resolving PersistentObjectException in Spring Boot

If you're developing a Spring Boot application that uses Hibernate for managing your database entities and encounter the error "PersistentObjectException: detached entity passed to persist", you're not alone. This issue can be particularly daunting for developers implementing a one-to-many relationship between entities, such as users and sales. In this post, we’ll explain what this error means and how you can resolve it effectively.

Understanding the Error

The specific error message indicates that you are trying to persist an entity that is no longer attached to the current Hibernate session. This usually happens when:

An entity instance is retrieved from the database, detached from the session, and later you are trying to persist it again.

You are trying to save a child entity without the proper reference to the parent entity.

Example Scenario

In your case, you are attempting to add a new sale (Sales entity) associated with a user (User entity). Here's a simplified version of the classes based on the provided structure:

User Class

Sales Class

Key Relationships

One user can have multiple sales (one-to-many relationship).

Steps to Fix the PersistentObjectException

Let’s break down the solution into clear, actionable steps.

1. Use Merge Instead of Persist

[[See Video to Reveal this Text or Code Snippet]]

Why?

2. Review Entity Annotations

While reviewing your entities, also check the annotations used for primary keys:

In your Sales class, you should ensure that policy_number is not marked with @ GeneratedValue if it is not auto-incrementing in your database.

[[See Video to Reveal this Text or Code Snippet]]

3. Ensure Proper Relationships

Make sure that when you create a new sale in your controller, you are setting the user reference appropriately.

For example:

[[See Video to Reveal this Text or Code Snippet]]

4. Testing the Changes

After making these changes, it's crucial to test that adding sales no longer leads to a PersistentObjectException. Create a few test cases to verify:

Adding a new sale for an existing user.

Ensuring that the merge method correctly saves the data without errors.

Conclusion

By implementing these changes, you should be able to resolve the PersistentObjectException effectively. Remember that carefully managing entity states and relationships in your Spring Boot application is vital for ensuring that your data operations run smoothly. If you run into additional challenges, reviewing your entity relationships and database definitions can often provide further insight.

Happy coding! If you have any questions or need further assistance, feel free to ask in the comments.