UserDO.java
@Data
@TableName("user")
public class UserDO {
@TableId
private Integer id;
private Integer pid;//父id
/* 其他属性略 */
/**
* 查询上级 一对一
*/
@TableField(exist = false)
@EntityMapping(thisField = "pid", joinField = "id")
private UserDO pUser;
/**
* 查询下级 一对多
*/
@TableField(exist = false)
@EntityMapping(thisField = "id", joinField = "pid")
private List<UserDO> childUser;
/**
* 带条件的查询下级 一对多
*/
@TableField(exist = false)
@EntityMapping(thisField = "id", joinField = "pid",
condition = {
@MPJMappingCondition(column = "sex", value = "0"),//sex = '0' 默认条件是等于
@MPJMappingCondition(column = "name", value = "张三", keyWord = SqlKeyword.LIKE)//name like '%a%'
},
apply = @MPJMappingApply(value = "id between 1 and 20"))//拼接sql 同 wrapper.apply()
private List<UserDO> childUserCondition;
/**
* 查询地址 (一对多)
*/
@TableField(exist = false)
@EntityMapping(thisField = "id", joinField = "userId")
private List<UserAddressDO> addressList;
/**
* 绑定字段 (一对多)
*/
@TableField(exist = false)
@FieldMapping(tag = UserDO.class, thisField = "id", joinField = "pid", select = "id")
private List<Integer> childIds;
}
使用
/**
* 一对一,一对多关系映射查询
* 映射只对以Deep结尾有效,比如 getByIdDeep listByIdsDeep 等
* 如果不需要关系映射就使用mybatis plus原生方法即可,比如 getById listByIds 等
*
* 注意:关系映射不会去关联查询,而是执行多次单表查询(对结果汇总后使用in语句查询,再对结果进行匹配)
*/
@SpringBootTest
class MappingTest {
@Resource
private UserMapper userMapper;
@Test
void test1() {
UserDO deep = userMapper.selectByIdDeep(2);
System.out.println(deep);
}
@Test
void test2() {
List<UserDO> list = userMapper.selectListDeep(Wrappers.emptyWrapper());
list.forEach(System.out::println);
}
@Test
void test3() {
Page<UserDO> page = userMapper.selectPageDeep(new Page<>(2, 2), Wrappers.emptyWrapper());
page.getRecords().forEach(System.out::println);
}
/**
* 更多方法请查阅 MPJDeepMapper 或者 MPJDeepService
* 使用方式与 mybatis plus 一致
*/
}
MPJMapping 说明:
- @EntityMapping / @FieldMapping tag 关联实体类
- @EntityMapping / @FieldMapping thisField 当前类关联对应的字段的属性名,可以不填,默认为当前类的主键
- @EntityMapping / @FieldMapping joinField 关联类对应的字段的属性名,可以不填,默认为关联类的主键
- @EntityMapping / @FieldMapping isThrowExp 一对一查询时,如果查询到多条记录是否抛出异常,true:抛出异常,false:获取列表第一条数据
更多功能请看代码注释 EntityMapping FieldMapping