MyBatis-Plus 注解方式（一对多、多对一）

我就是我 2023-09-30 08:07 6阅读 0赞

UserMapper.java

@Repository
    public interface UserMapper extends BaseMapper<User> {
        
    	//多对一
        @Results(value = {
        
                @Result(property = "id", column = "id"),
                @Result(property = "name", column = "name"),
                @Result(property = "age", column = "age"),
                @Result(property = "email", column = "email"),
                @Result(property = "dept", column = "deptid", one = @One(select = "com.atguigu.mybatisplus.mapper.DeptMapper.selectById")),
        })
        @Select("select id, name, age, email, deptid from t_user")
        List<UserVO> getUserDept();
    
        @Select("select id, name, age, email from t_user where deptid=#{deptid}")
        List<User> getUserByDeptId(@Param("deptid") int deptid);
    }

DeptMapper.java

public interface DeptMapper extends BaseMapper<Dept> {
        
    	//一对多
        @Results(value = {
        
                @Result(property = "id", column = "id"),
                @Result(property = "name", column = "name"),
                @Result(property = "users", column = "id", many = @Many(select = "com.atguigu.mybatisplus.mapper.UserMapper.getUserByDeptId")),
        })
        @Select("select id, name from t_dept")
        List<DeptVO> getDeptUser();
    }

DeptVO

@Data
    public class DeptVO {
        
    
        private Integer id;
    
        private String name;
    
        private List<User> users;
    }

UserVO

@Data
    public class UserVO {
        
        private int id;
        
        private String name;
        
        private int age;
        
        private String email;
        
        private Dept dept;
    }

调用

@SpringBootTest
    class MybatisplusApplicationTests {
        
    
        @Resource
        private IUserService userService;
    
        @Resource
        private IDeptService deptService;
    
        @Test
        void contextLoads() {
        
            List<UserVO> userDept = userService.getUserDept();
            userDept.forEach(System.out::println);
    
            List<DeptVO> deptUser = deptService.getDeptUser();
            deptUser.forEach(System.out::println);
        }
    
    }