Why Doesn't the Delete Method in Spring Data JPA Return Any Values?

What is the reason that the delete method in Spring Data JPA does not return any values?

@Transactional
public interface UserRepository extends JpaRepository<User, Long> {
    void deleteById(Long id);
}

In Spring Data JPA, the delete method is designed to perform a specific action: removing an entity from the database. However, it does not return any values. This design choice is rooted in the principles of simplicity and declarative programming in JPA, focusing on the command itself rather than its results.

// Custom delete method that returns whether the deletion was successful.
@Query("DELETE FROM User u WHERE u.id = :id")
int deleteUserById(@Param("id") Long id);

Causes

• The delete operation is fundamentally a command rather than a query. It indicates to the database that a record should be removed without the need for confirmation or response.
• In relational databases, a successful deletion does not generally require returning the deleted entity. The impact (success or failure) can often be determined through exceptions or the state of the repository after the operation.
• Using void as the return type simplifies the interface and emphasizes that the purpose of the method is to enact a change, not retrieve data.

Solutions

• If you need feedback on whether a deletion was successful, handle exceptions such as `EntityNotFoundException` which can indicate if an entity was not found for deletion.
• Consider implementing custom repository methods that return boolean values or the number of affected rows if you require more detailed feedback from your delete operations.

Mistake: Assuming the delete method will return the deleted entity or a success flag.

Solution: Understand that in JPA, the delete method's behavior is intentional; handle it through exceptions or custom queries.

Mistake: Not handling the potential exceptions when performing a delete operation.

Solution: Ensure your code includes exception handling to gracefully deal with cases where an entity may not be found.