Fix: Hibernate 7 & JPA Strict Mode In Spring Data JPA 4.0

Hey guys! Let's dive into a tricky situation involving Hibernate 7, Spring Data JPA 4.0.0-M6, and fully qualified entity names. I've been wrestling with this, and I think it's something we can all learn from. The core issue revolves around how Spring Data JPA constructs JPQL queries, specifically when hibernate.jpa.compliance is enabled, and how Hibernate 7 interprets these queries. I'll break it down, so we can understand what's happening and how to potentially fix it.

The Setup: Spring Boot, Hibernate, and JPA Compliance

First off, here's the environment that triggers the problem. I was running Spring Boot 3.5.6 with Hibernate 6.6.29, but I'm trying to move to Spring Boot 4.0.0-M3 with Hibernate 7.1.2. Importantly, I'm using Spring Data JPA 4.0.0-M6. Our application has the hibernate.jpa.compliance option set, which is designed to enforce stricter checks on our JPQL queries. This is a good thing in the long run because it helps catch potential issues early on, but it can also reveal some compatibility snags, as we'll see. The hibernate.jpa.compliance setting is crucial here because it activates the strict mode that exposes the problem. This setting is often used to ensure that the application adheres strictly to the JPA specifications, leading to more robust and portable code. Without this setting, the issue wouldn’t surface.

Our application uses a repository interface that extends CrudRepository and PagingAndSortingRepository. This setup is pretty standard for Spring Data JPA applications. When Spring Data JPA does its thing and generates queries, it allocates a org.springframework.data.jpa.repository.query.JpqlQueryBuilder.Entity object. This object contains information about the entity, like the fully qualified name and the alias used in the query. This is a crucial step in constructing the JPQL query. The Entity object holds important details that will be used to build the final SQL query. This includes the entity's name (like com.myorg.app.model.Foo), its simple name (Foo), and the alias (e.g., f). These pieces of information are essential for the query builder to correctly reference the entities in the database.

The Query Generation Process and the Problem

Let's walk through the query generation to pinpoint where things go wrong. When we call a repository method that generates a SELECT query, the process eventually ends up in org.springframework.data.jpa.repository.query.JpqlQueryBuilder.Select. This is where the SQL query gets put together. The code in question looks something like this:

StringBuilder result = new StringBuilder(
        "SELECT %s FROM %s %s".formatted(selection.render(renderContext), entity.getEntity(), entity.getAlias()));

Here, the entity.getEntity() method is used to get the fully qualified name of the entity. This method is key to understanding the issue. The formatted SQL then looks like this:

SELECT f FROM com.myorg.app.model.Foo f

This SQL is then passed along until it enters Hibernate, specifically into org.hibernate.query.hql.internal.SemanticQueryBuilder.checkFQNEntityNameJpaComplianceViolationIfNeeded. The problem arises in this function. It checks that the entity name in the query matches the entity descriptor. Here's where the mismatch happens. The name value passed into this function is com.myorg.app.model.Foo, while entityDescriptor.jpaEntityName is Foo. This difference triggers an exception and causes the query to fail. Hibernate expects the simple name, but Spring Data JPA is providing the fully qualified name. This discrepancy is what causes the JpaComplianceViolationException.

The Root Cause: Mismatched Entity Names

To sum up, the core of the problem lies in how Spring Data JPA constructs the SQL query. It uses the fully qualified name (com.myorg.app.model.Foo) when generating the SELECT statement. However, Hibernate, when running in strict JPA compliance mode, expects the simple name (Foo). The different expectations between Spring Data JPA and Hibernate, especially with hibernate.jpa.compliance enabled, cause the JpaComplianceViolationException. The SQL query is being constructed in a way that doesn't align with Hibernate's expectations when it comes to entity name handling.

Potential Solutions and Workarounds

So, what can we do? Here are a few approaches to tackle this issue:

1. Code Bug or Feature?: The ideal fix, according to me, is for Spring Data JPA to use entity.getName() instead of entity.getEntity(). This would pass the Hibernate checks. It appears to be a potential bug. It seems like the StringBuilder creation should use entity.getName() to match Hibernate's expectations. However, there's no clear documentation stating that the Hibernate JPA compliance option is fully supported. This fix would ensure consistency between how the query is constructed and how Hibernate validates it.

2. Disable JPA Compliance (Temporary): Disabling hibernate.jpa.compliance does indeed fix the problem by suppressing the check. This is the simplest workaround, but it's not ideal since it means you're not getting the benefit of those stricter JPA checks. It's fine as a temporary measure, but it's not a long-term solution.

3. Custom Query Methods (Alternative): Another possible workaround is to write custom query methods. If you can rewrite the queries to use the simple entity name directly, you can avoid the conflict. This might involve using @Query annotations and manually writing JPQL. It is more involved. This approach gives you more control over the query and allows you to ensure the entity names match Hibernate's expectations.

4. Check for Updates: Keep an eye on Spring Data JPA and Hibernate releases. This might be fixed in future updates. It's worth checking the release notes for any changes related to JPA compliance or entity name handling. Both Spring and Hibernate teams are actively working to improve their frameworks, and this issue might be addressed in a future release.

Conclusion: A Call for Action

So, is this a code bug, or is it a feature limitation? Personally, it feels like a code bug in Spring Data JPA, but I haven't found definitive documentation stating that the Hibernate JPA compliance option is fully supported. It is up for grabs for discussion. The option to disable it also fixes the issue. The best path forward is likely to open a bug report or a discussion on the Spring Data JPA issue tracker. Provide the details of the problem, including the Spring Data JPA and Hibernate versions, and the specific code that reproduces the issue. This will help the developers understand the issue and potentially fix it. The Spring Data JPA community can provide insights and suggest solutions or workarounds.

Also, consider checking Hibernate's documentation to see if there are any specific recommendations for integrating with Spring Data JPA and using the hibernate.jpa.compliance option. There might be specific guidelines or configurations that can help avoid this issue.

I hope this breakdown is helpful. Let me know what you guys think, and if you've found any other solutions! This is a common issue, and sharing information can help us all!

For further reading, please visit these helpful links:

• Spring Data JPA Documentation: https://spring.io/projects/spring-data-jpa - This is a great resource for understanding how Spring Data JPA works and for finding any related documentation or known issues.

• Hibernate Documentation: https://hibernate.org/orm/ - Check this website for the Hibernate documentation and learn more about the JPA compliance mode.