忽略空参数的Spring Data JPA命名查询

Question

@Repository
public interface EntityRepository extends JpaRepository<Entity, Long> {

    List<Entity> findAllByFirstId(Long firstId);
    List<Entity> findAllBySecondId(Long secondId);
    List<Entity> findAllByFirstIdAndSecondId(Long firstId, Long secondId);
}

ResponseEntity<List<Entity>> entities(Optional<Long> firstId, Optional<Long> secondId);

public List<Entity> entities(Optional<Long> firstId, Optional<Long> secondId) {

    return firstId
        .or(() -> secondId)
        .map(value -> {
            if (firstId.isEmpty()) {
                return entityRepository.findAllBySecondId(value);
            }
            if (secondId.isEmpty()) {
                return entityRepository.findAllByFirstId(value);
            }
            return entityRepository.findAllByFirstIdAndSecondId(
            firstId.get(), secondId.get());
        })
        .orElse(entityRepository.findAll())
        .stream()
        .map(...)     // Mapping between DTO and entity. For sake of brevity
                      // I used the same onject Entity for both controler and repository 
                      // as long as it not related to the question   

        .collect(Collectors.toList());
}

这个问题已经问过了：Spring data-ignore参数，如果它有一个空值和一个创建的票证，datajpa-209。

只要这个问题是近3年前的问题，而且票证可以追溯到2012年，我就想问是否有一种更舒适和通用的方法来避免处理可选的和复制存储库方法的开销。2个这样的参数的解决方案看起来是可以接受的，但是我想实现4-5个参数的非常相同的过滤。

Answer 1

您需要这样的规范实用程序类

public class EntitySpecifications {
    public static Specification<Entity> firstIdEquals(Optional<Long> firstId) {// or Long firstId. It is better to avoid Optional method parameters.
        return (root, query, builder) -> 
            firstId.isPresent() ? // or firstId != null if you use Long method parameter
            builder.equal(root.get("firstId"), firstId.get()) :
            builder.conjunction(); // to ignore this clause
    }

    public static Specification<Entity> secondIdEquals(Optional<Long> secondId) {
        return (root, query, builder) -> 
            secondId.isPresent() ? 
            builder.equal(root.get("secondId"), secondId.get()) :
            builder.conjunction(); // to ignore this clause
    }
}

然后您的EntityRepository必须扩展JPaspecificationExecutor

@Repository
public interface EntityRepository 
    extends JpaRepository<Entity, Long>, JpaSpecificationExecutor<Entity> {

}

用法：

@Service
public class EntityService {    

    @Autowired
    EntityRepository repository;

    public List<Entity> getEntities(Optional<Long> firstId, Optional<Long> secondId) {
        Specification<Entity> spec = 
            Specifications.where(EntitySpecifications.firstIdEquals(firstId)) //Spring Data JPA 2.0: use Specification.where
                          .and(EntitySpecifications.secondIdEquals(secondId));

        return repository.findAll(spec);        
    }
}