Java Spring Data JPA：查询多对多
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Spring Data JPA: query ManyToMany
提问by qwe asd
I have entities Userand Test
我有实体User和Test
@Entity
public class User {
private Long id;
private String userName;
}
@Entity
public class Test {
private Long id;
@ManyToMany
private Set<User> users;
}
I can get all tests by User entity:
我可以通过用户实体获得所有测试：
public interface TestRepository extends JpaRepository<EventSettings, Long> {
List<Test> findAllByUsers(User user);
}
But which query can I use for finding all tests by userName?
但是我可以使用哪个查询来查找所有测试userName？
采纳答案by Tunaki
The following method signature will get you want to want:
以下方法签名将使您想要：
List<Test> findByUsers_UserName(String userName)
This is using the property expressionfeature of Spring Data JPA. The signature Users_UserNamewill be translated to the JPQL x.users.userName. Note that this will perform an exact match on the given username.
这是使用Spring Data JPA的属性表达式功能。签名Users_UserName将被转换为 JPQL x.users.userName。请注意，这将对给定的用户名执行完全匹配。
回答by ArslanAnjum
Other answer shows how to achieve desired functionality using function naming technique. We can achieve same functionality using @Query annotation as follows:
其他答案显示了如何使用函数命名技术实现所需的功能。我们可以使用 @Query 注释实现相同的功能，如下所示：
@Query("select t from Test t join User u where u.username = :username")
List<Test> findAllByUsername(@Param("username")String username);
