Solving the json_column Mapping Issue in Hibernate 6 with Custom Types

Learn how to effectively map `jsonb` columns to POJOs in Hibernate 6 during your Spring Boot migration.
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Handling JSON Column Mapping in Hibernate 6

Migrating applications, particularly when switching between versions of frameworks like Spring Boot, can introduce various challenges. One common issue developers face is managing changes in how ORM libraries handle SQL data types.

In this post, we address a specific problem: how to map a jsonb column in PostgreSQL to a POJO in Hibernate 6, particularly when migrating from Spring Boot 2. We found that the previous method using addScalar for JSON column mapping is no longer effective. Let's take a closer look at the issue and the solution.

The Problem: Native Query and JSON Mapping

When using Hibernate types to run native queries, developers could traditionally map results from a JSON column to a POJO as follows:

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

However, in Hibernate 6, the line that uses addScalar to map the json_column has become ineffective:

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

This change in the API poses a significant challenge for ensuring that your application continues to work seamlessly after migration.

The Solution: Using CustomType for JSON Columns

To resolve this issue, we need to adapt our code to the new way Hibernate 6 handles such mappings. Instead of using JsonBinaryType directly with addScalar, we will leverage the CustomType class, which allows us to specify the configuration for JSON mapping.

Here’s how to adjust your native query:

Step-by-step Adjustment

Replace the old addScalar mapping for the JSON column.

Utilize CustomType to wrap the JsonBinaryType.

Here’s the modified code:

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

Full Example Code

With the adjustment, your database query might now look like this:

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

Conclusion

Migrating from Spring Boot 2 to 3 and adapting to Hibernate 6 introduces new challenges, particularly in JSON column mapping. By understanding the necessary adjustments in your native queries—like switching to a CustomType for JSON mappings—you can ensure your application remains functional and efficient.

Make sure to test thoroughly after your migration to resolve any other potential issues that could arise from new library versions. Happy coding!