mybatis查询返回一个对象中带有集合
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mybatis查询返回一个对象中带有集合
1.首先创建两个测试类
@Data@TableName("z_test_grade")public class ZTestGradeEntity implements Serializable {
private Integer id;
private String name;
private String address;}@Data@TableName("z_test_teacher")public class ZTestTeacherEntity implements Serializable { @TableId(type = IdType.AUTO) private Integer id;
private String name;
private Integer age;
private String categroy;
private String level;
private Integer gradeldId; //关联主表id}2.创建返回类Dto 用来接收查询出来的结果
@Datapublic class ResultDto { private Integer id;
private String name;
private String address;
private List<ZTestTeacherEntity> teacherList;}3.重点：然后配置xml
//<-- 关联集合就是用collection--><resultMap id="gradeMap" type="com.personal.modules.test.ResultDto"> <id column="id" property="id" /> <result column="name" property="name"/> <result column="address" property="address"/> <collection property="teacherList" ofType="com.personal.modules.test.ZTestTeacherEntity"> <id property="id" column="t_id" /> <result column="t_name" property="name"/> <result column="t_age" property="age"/> <result column="t_categroy" property="categroy"/> <result column="t_level" property="level"/> <result column="t_gradeldId" property="gradeldId"/> </collection> </resultMap>常用的属性就不说了，特别要注意的是ofType这个要指向各自表的实体类，然后子表的column属性不要和主表重名，一旦重名就会出问题，不知道是不是我配置的问题，希望有大佬指教，反正不重名就可以 接下来就是查询语句了，很简单，只要别名和上面resultMap对的上就ok
4.SQL
//SQL:<select id="test" resultMap="gradeMap"> SELECT ztg.id, ztg.name, ztg.address, ztt.id as t_id, ztt.name as t_name, ztt.age as t_age, ztt.categroy as t_categroy, ztt.level as t_level, ztt.gradeld_id as t_gradeldId FROM z_test_grade ztg LEFT JOIN z_test_teacher ztt ON ztt.gradeld_id = ztg.id
</select>5.返回结果数据
{ "code":200, "data":[ { "id":1, "name":"3年一班", "address":"1楼", "teacherList":[ { "id":1, "name":"宋元桥", "age":50, "categroy":"武当", "level":"1", "gradeldId":1 }, { "id":2, "name":"俞莲舟", "age":43, "categroy":"武当", "level":"1", "gradeldId":1 } ] }, { "id":2, "name":"3年二班", "address":"2楼", "teacherList":[ { "id":3, "name":"张三", "age":55, "categroy":"武当", "level":"1", "gradeldId":2 } ] } ]}文章分享
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mybatis查询返回一个对象中带有集合
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