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Learn how to effectively apply a custom hibernate table naming strategy in Grails 5, ensuring your database tables follow the desired naming convention.
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Custom Hibernate Table Naming Strategy in Grails 5

Introduction

If you're developing an application using Grails 5, you might come across the need to customize your Hibernate table naming strategy. Specifically, you may want to implement table prefixes for your database tables created by GORM/Hibernate. However, transitioning to this version of Grails has posed challenges for developers accustomed to previous methods of customizing table names. In this post, we'll explore the problem and provide a clear solution to applying a custom naming strategy to your Hibernate tables seamlessly.

The Challenge

In earlier versions of Grails, it was straightforward to set table prefixes using the naming_strategy property within the Hibernate configuration. However, with the introduction of Hibernate 5, many of the previous methods have become ineffective. Developers have reported that custom naming classes appear to be ignored despite attempts in various configuration files, such as application.yml or application.groovy.

You might find yourself in a situation where you've created a custom naming strategy class, like the one below:

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

Even when attempting to configure the naming strategy like this:

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

You may still find that the generated table name does not reflect the desired prefix, remaining simply as customer instead of customprefix_customer for your domain named Customer.

Understanding the Solution

After grappling with this issue, the solution lies in how you declare your custom naming strategy class. Adjustments in Grails 5 mean that direct instantiation with a constructor is no longer supported. Here’s a breakdown of the adjustments you need to make:

Class Declaration

Previously, in config.groovy, the naming strategy might have been instantiated directly using a constructor:

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

This method allowed for dynamic prefixes across different environment blocks. In Grails 5, however, the proper way to declare your naming strategy has simplified to just specifying the class name, as follows:

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

Setting Configuration Variables

Since you can no longer pass parameters to the constructor, you will need to take a slightly different approach to accommodate dynamic table prefixes. Here’s how to do it:

Define a Configuration Variable: Set a variable in your Grails configuration to hold the table prefix.

Read in the Configuration: Modify your MyCustomStrategy class to read this configuration variable. This way, your class can dynamically apply the prefix as needed.

This adjustment provides a workable solution. However, it's essential to keep in mind that while this methodology resolves the immediate issue, the naming_strategy method is deprecated. The recommendation from Hibernate is to transition to using PhysicalNamingStrategy and ImplicitNamingStrategy. It’s advisable to keep an eye on future updates from the Grails team regarding support for these strategies.

Conclusion

By following these steps to adjust your custom Hibernate table naming strategy in Grails 5, you can effectively add prefixes to your database tables. Remember to keep an eye out for updates that may improve or change the handling of naming strategies in future Grails releases. Happy coding!