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Discover how to effectively manage `generated columns` in Quarkus Panache entities using Hibernate's annotations. This guide will provide a clear solution to the problems encountered with generated columns.
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This video is based on the question https://stackoverflow.com/q/78114604/ asked by the user 'JaB' ( https://stackoverflow.com/u/5276170/ ) and on the answer https://stackoverflow.com/a/78114907/ provided by the user 'Luca Basso Ricci' ( https://stackoverflow.com/u/2587166/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Handling Generated Columns in Quarkus Panache Entity

In the world of database management, generating column values based on other fields is a common practice to enhance data integrity and accessibility. However, when developing applications with Quarkus and using Panache as an ORM framework, you may encounter challenges related to these generated columns. One such issue arises when trying to persist an entity that has a generated column, resulting in exceptions that can put a halt to your development process.

In this guide, we will delve into the problem of using generated columns in a Quarkus Panache entity and provide a comprehensive solution to ease the implementation.

The Problem

Imagine you have a database table called myentity, with a column weeklyhour that is calculated from two other integer fields: weekday and hour. After executing a Flyway migration script to create this generated column, you encounter an issue with Hibernate when trying to persist your entity. The error message reads:

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

This indicates that the Hibernate ORM is attempting to insert a value into a generated column, which is not permissible by the database. The question is: how can you tell Hibernate that the column weeklyhour is computed and should not be set manually during persisting?

The Solution

Understanding the Hibernate Annotations

To resolve this issue, you need to make appropriate use of Hibernate's annotations to inform the ORM about the generated column's behavior. There are two primary approaches you can take:

Using @Formula Annotation:

By using the @Formula annotation, you can directly inform Hibernate about how to compute the value of the weeklyhour column.

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

Using @Column Annotation:

Alternatively, you can leverage the @Column annotation to specify that this field is not insertable or updatable, which effectively means that Hibernate should ignore it during insert operations:

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

Implementation Details

Here is how your entity should look incorporating either of the above solutions:

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

Final Thoughts

By leveraging the appropriate annotations provided by Hibernate, you can seamlessly integrate generated columns into your Quarkus Panache entities without encountering persistence errors. This setup ensures that your application maintains clean data management practices while also allowing you to benefit from generated columns' computational capabilities.

Implementing these solutions not only resolves your current issue but also helps future-proof your application against similar scenarios.

If you have any further questions or need assistance with your implementation, feel free to reach out. Happy coding!