Mybatis中查询复杂映射结构

一、结果包含子列表

0.Bean

public class School{
    //其他略
    private String schoolName;
    private List<Student> studentList;
}

1.定义resultMap

<resultMap type="School" id="SchoolResult">
    <result property="id" column="id"/>
    <result property="schoolName" column="school_name" />
    <result property="createUser" column="create_user"/>
    <result property="createUserId" column="create_user_id"/>
    <result property="createTime" column="create_time"/>
</resultMap>

<resultMap type="Student" id="StudentResult">
    <result property="id" column="id"/>
    <result property="schoolId" column="school_id"/>
    <result property="studentName" column="student_name" />
    <result property="createUser" column="create_user"/>
    <result property="createUserId" column="create_user_id"/>
    <result property="createTime" column="create_time"/>
</resultMap>

<resultMap id="ShcoolStudentResult" type="Student" extends="SchoolResult">
    <collection property="studentList" notNullColumn="sub_id" javaType="java.util.List" resultMap="StudentResult"/>
</resultMap>

2.select语句

<select id="selectSchoolStudentById" parameterType="String"
            resultMap="ShcoolStudentResult">
        select a.id,
               a.create_user,
               a.create_user_id,
               a.create_time,
               a.school_name,
               b.id                   as sub_id,
               b.create_user          as sub_create_user,
               b.create_user_id       as sub_create_user_id,
               b.create_time          as sub_create_time,
               b.student_name         as sub_student_name,
    		   b.school_id            as sub_school_id,	
        from school a
                 left join student b on b.school_id = a.id
        where a.id = #{id}
    </select>

3.使用

School schoolInfo = SchoolMapper.selectSchoolStudentById(id);
//返回的School对象就带有Student列表信息

4.注意事项！

PageHepler分页插件不支持嵌套结果映射
[参考文档]: https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/Important.md

[参考解决方案]: https://blog.csdn.net/weixin_41869361/article/details/116427385

二、结果包含子对象