使用Enum和JPA Repository的查询方法

Question

我有实体Driver和枚举DriverLanguage。我想得到一个驱动程序的列表，他们可以通过参数在存储库方法中选择语言。

...
@Entity
public class Driver{
private Long id;
private firstName;
@ElementCollection(targetClass = DriverLanguage.class)
@Enumerated(EnumType.STRING)
@CollectionTable(name = "driver_language",
joinColumns = @JoinColumn(name = "driver_language_id"))
@Column(name = "driver_language")
private Set<DriverLanguage> languages = new HashSet<>();
}
public enum DriverLanguage {
ENGLISH,
GERMAN
}

现在我使用@Query方法。

我的第一个方法：

@Repository
public interface DriverRepository extends JpaRepository<Driver, Long> {
@Query("SELECT d "
+ "FROM Driver d "
+ "JOIN DriverLanguage dl on d.id = dl.driver_language_id "
+ "WHERE dl.driver_language = ?1")
List<Driver> findByLanguage(String language);
}
ERROR: Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: Path expected for join!

然后我读到也许我不应该使用JOIN，所以我尝试了这个：

@Repository
public interface DriverRepository extends JpaRepository<Driver, Long> {
@Query("SELECT d "
+ "FROM Driver d, DriverLanguage dl "
+ "WHERE d.id = dl.driver_language_id AND dl.driver_language = ?1")
List<Driver> findByLanguage(String language);
}
ERROR: Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: DriverLanguage is not mapped

我在这里缺少什么？

Answer 1

直接的JPQL查询可以是

@Repository
public interface DriverRepository extends JpaRepository<Driver, Long> {
@Query("SELECT d "
+ "FROM Driver d "
+ "WHERE ?1 MEMBER OF d.languages")
List<Driver> findByLanguage(DriverLanguage language);
}

错误消息告诉你：

• 路径为d.languages(属性名称(
• DriverLanguage不是实体