`deleteBy` returning primitive number queries fail with `ClassCastException`

[raitool]

In 3.5.3 the following worked fully:

@Repository
public interface BookRepository extends JpaRepository<Book, Long> {

    long deleteByTitle(String title);

    Long deleteByAuthor(String author);

    List<Book> deleteByLanguage(String language);
}

In 3.5.4 it does not - deleteByTitle throws one of the following

• class ee.ooloros.example.springdatajpa.entities.Book cannot be cast to class java.lang.Long
• Delete query returned more than one element: expected 1, actual 2

I created the following tests to demo what's working (and what's not).

    @Test
    void shouldDeleteOneByTitle() {
        // fails - class ee.ooloros.example.springdatajpa.entities.Book cannot be cast to class java.lang.Long
        long count = bookRepository.deleteByTitle("Pride and Prejudice");
        assertThat(count).isEqualTo(1);
    }

    @Test
    void shouldDeleteMultipleByTitle() {
        // fails - Delete query returned more than one element: expected 1, actual 2
        long count = bookRepository.deleteByTitle("The Trial");
        assertThat(count).isEqualTo(2);
    }

    @Test
    void shouldDeleteOneByAuthor() {
        Long count = bookRepository.deleteByAuthor("Victor Hugo");
        assertThat(count).isEqualTo(1);
    }

    @Test
    void shouldDeleteMultipleByAuthor() {
        Long count = bookRepository.deleteByAuthor("Franz Kafka");
        assertThat(count).isEqualTo(2);
    }

    @Test
    void shouldDeleteByLanguage() {
        List<String> expected = List.of("Don Quixote", "One Hundred Years of Solitude");

        List<Book> deleted = bookRepository.deleteByLanguage("Spanish");
        assertThat(deleted)
                .extracting(Book::getTitle)
                .isEqualTo(expected);
    }

the full code is to recreate/confirm the issue is in https://github.com/raitool/spring-data-jpa-3.5.4-error/blob/main/src/test/java/ee/ooloros/example/springdatajpa/repositories/BookRepositoryTest.java
(and the domain-example was taken from https://www.baeldung.com/spring-data-jpa-delete along with long deleteByTitle(String title);)

PS: The bug was introduced with #3995

[essaysir]

I've been investigating this issue and found that the root cause is in the DeleteExecution.doExecute() method in JpaQueryExecution.java:

if (simpleBatch) {
    return resultList.size();  // Always returns int
}

The problem is that resultList.size() always returns int, but when the method signature expects long or Long, this causes a ClassCastException.

Proposed fix:

if (simpleBatch) {
    if (ClassUtils.isAssignable(jpaQuery.getQueryMethod().getReturnType(), Long.class)) {
        return (long) resultList.size();
    }
    return resultList.size();
}

Questions:

1. Would it be okay for me to work on this fix and submit a PR?
2. Is this approach acceptable, or would you prefer a different solution?

Thanks!.

[mp911de]

Thanks for reaching out and looking into this. The assignability check should rather use ClassUtils.isAssignable(Number.class, returnType) because we convert any resulting number to the target type hence we're using the flipped check here. In a scenario where there would have been no converter involved, swapping returnType and Long.class (as seen above) would be appropriate.

I've addressed this change already and aligned the modifying execution in a similar way.