Spring Data JPA Bug: Combined @Query and Pageable Methods Cause Startup Failure

Encountering startup failures in your Spring Data JPA application? A subtle bug may be lurking when you combine @Query annotations with Pageable in your repository methods. This article dives into the details of this Spring Data JPA regression, its causes, and how to address it.

The Problem: IllegalStateException on Startup

The issue manifests as an java.lang.IllegalStateException during application startup, specifically when Spring tries to load the ApplicationContext. The error message points to a failure in creating a query for a repository method that uses both a @Query annotation and Pageable.

Here's a simplified scenario showcasing the problem:

public interface TestTableRepository extends JpaRepository<TestTable, Long> {

    @Query("SELECT t FROM TestTable t WHERE t.someField = :someValue")
    Page<TestTable> doesNotWork(Long someValue, Pageable pageable);
}

The logs show a failure during the creation of the bean for the specific repository, with a root cause indicating count query validation failure:

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'testTableRepository'...
Reason: Count query validation failed for method public abstract org.springframework.data.domain.Page ...

Why This Happens: Implicit SELECT and Pageable

The root cause lies in how Spring Data JPA handles @Query annotations combined with Pageable. When a @Query with an implicit SELECT (i.e., not explicitly selecting columns) is used alongside Pageable, Spring Data JPA attempts to automatically generate a count query for pagination purposes.

However, the automatic count query generation can fail in certain scenarios, leading to the IllegalStateException.

How to Fix Spring Data JPA Startup Failures

Here are a few steps you can take to resolve issues when combining @Query and Pageable:

• Explicitly Define the Count Query: The most robust solution is to provide an explicit count query within the @Query annotation. By doing so, you bypass Spring Data JPA's automatic count query generation that can fail.

  public interface TestTableRepository extends JpaRepository<TestTable, Long> {
  
      @Query(value = "SELECT t FROM TestTable t WHERE t.someField = :someValue",
             countQuery = "SELECT count(t) FROM TestTable t WHERE t.someField = :someValue")
      Page<TestTable> worksFine(Long someValue, Pageable pageable);
  }
  

  Copy

• Simplify the Query (If Possible): In some cases, refactoring the query to leverage Spring Data JPA's derived query methods can avoid the issue. However, this isn't always feasible for complex queries.

• Review Spring Data JPA Version: While this is reported as a regression, try upgrading your Spring Data JPA dependency to the latest version. Bug fixes are frequently released. Check release notes to confirm this one is addressed explicitly.

Preventing Future Issues

To prevent future occurrences of this Spring Data JPA bug, follow these best practices:

• When using @Query with Pageable, strongly consider providing an explicit countQuery. This approach provides greater control and avoids potential issues with automatic query generation.
• Thoroughly test your repository methods, especially those that combine @Query and Pageable, to catch any potential issues early in the development cycle. Catching these Spring Data JPA regressions early can save development time.

By understanding the cause of this issue and implementing the suggested solutions, you can effectively address Spring Data JPA regressions and ensure the stability of your Spring Data JPA applications.