Скачать или смотреть How to Auto Generate UUID Values for Non-Primary Keys Using JPA

Discover how to seamlessly auto-generate UUID values for non-primary keys in your Spring Boot application using JPA. This comprehensive guide walks you through the solution step by step!
---
This video is based on the question https://stackoverflow.com/q/62777718/ asked by the user 'Mohit224' ( https://stackoverflow.com/u/1134835/ ) and on the answer https://stackoverflow.com/a/62777860/ provided by the user 'Bala' ( https://stackoverflow.com/u/1983465/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to Auto generate UUID value for non-primary key using JPA

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Auto Generate UUID Values for Non-Primary Keys Using JPA

When building applications with a database, unique identifiers for records are critical. However, not all identifiers need to be primary keys. In this post, we will tackle a common scenario for Spring Boot developers facing the challenge of auto-generating UUID values for non-primary keys using JPA.

The Problem: Null Values on Insert

In a Spring Boot application using JPA to communicate with PostgreSQL, you may be working with a non-primary key that requires a UUID. Your current setup might look something like this:

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

However, upon calling the save method, you notice that the column value is null. This can be frustrating! You have also defined the column in your PostgreSQL database as:

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

The question then arises: How can you auto-generate the non-primary UUID value in this case?

The Solution: Using JPA Callbacks

One effective approach to solve this problem is to utilize JPA callbacks, specifically the @ PrePersist annotation. This allows you to define a method that will be executed just before an entity is persisted (saved) to the database.

Step-by-Step Implementation

Define a Method with @ PrePersist
Create a method in your entity class that generates a UUID value prior to the entity being saved.

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

In this function:

We call java.util.UUID.randomUUID() to generate a new UUID.

The generated UUID is then set to the userUuid field, ensuring that it receives a value before insertion into the database.

Update Your Entity Class
Ensure that your entity class includes the @ PrePersist annotated method along with the UUID field definition.

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

Handling the Database Column
Make sure your database column is properly defined to accept UUID values. Your SQL command is perfectly fine:

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

This setup will allow you the flexibility to use your Java method for UUID generation while maintaining defaults at the database level.

Conclusion

By implementing JPA callbacks, specifically leveraging the @ PrePersist annotation, you effectively resolve the issue of generating UUID values for non-primary keys when using JPA in a Spring Boot application. This method ensures that each time you save an entity, a unique UUID is generated and assigned seamlessly.

In conclusion, follow the above steps to ensure automatic UUID generation without complications, elevating the integrity of your application’s data management.

Feel free to reach out if you have further questions regarding UUID generation or similar JPA-related issues. Happy coding!