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Mybatis 返回对象中包含多个 List<String>属性

巧乐兹_d41f 2022-12-03 阅读 80


数据库数据

mysql> select * from ai_user;
+----+-----------+--------+
| id | user_name | status |
+----+-----------+--------+
| 1 | Answer | 1 |
| 2 | Iris | 1 |
+----+-----------+--------+

mysql> select * from ai_name;
+---------+-----------+
| user_id | user_name |
+---------+-----------+
| 1 | Answer |
| 1 | AI |
| 1 | AAL |
| 2 | Iris |
| 2 | Ellis |
| 2 | Monta |
+---------+-----------+

mysql> select * from ai_role;
+---------+-----------------+
| user_id | role_name |
+---------+-----------------+
| 1 | Admin |
| 1 | Manager |
| 1 | Coder |
| 2 | CustomerService |
+---------+-----------------+

 

实体类

@Data
public class User {
private Long id;
private List<String> names;
private List<String> roles;
}

 

Mapper 层

public interface UserMapper {
List<User> queryUsers();
}

 

Mapper Sql 映射文件

<resultMap id="UserMap" type="User">
<result column="id" property="id" jdbcType="BIGINT" />
<collection property="names" resultMap="NamesMap" />
<collection property="roles" resultMap="RolesMap" />
</resultMap>

<resultMap id="NamesMap" type="string">
<result column="user_name" />
</resultMap>

<resultMap id="RolesMap" type="string">
<result column="role_name" />
</resultMap>

<select id="queryUsers" resultMap="UserMap">
SELECT au.id, an.user_name, ar.role_name
FROM ai_user au
LEFT JOIN ai_name an ON an.user_id = au.id
LEFT JOIN ai_role ar ON ar.user_id = au.id
</select>

 

结果输出示例

{"id":1,"names":["Answer","AI","AAL"],"roles":["Admin","Manager","Coder"]}
{"id":2,"names":["Iris","Ellis","Monta"],"roles":["CustomerService"]}

 

数据库脚本

DROP TABLE IF EXISTS `ai_name`;
CREATE TABLE `ai_name` (
`user_id` bigint(18) NOT NULL,
`user_name` varchar(55) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

-- ----------------------------
-- Records of ai_name
-- ----------------------------
INSERT INTO `ai_name` VALUES ('1', 'Answer');
INSERT INTO `ai_name` VALUES ('1', 'AI');
INSERT INTO `ai_name` VALUES ('1', 'AAL');
INSERT INTO `ai_name` VALUES ('2', 'Iris');
INSERT INTO `ai_name` VALUES ('2', 'Ellis');
INSERT INTO `ai_name` VALUES ('2', 'Monta');

-- ----------------------------
-- Table structure for `ai_role`
-- ----------------------------
DROP TABLE IF EXISTS `ai_role`;
CREATE TABLE `ai_role` (
`user_id` bigint(18) NOT NULL,
`role_name` varchar(55) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

-- ----------------------------
-- Records of ai_role
-- ----------------------------
INSERT INTO `ai_role` VALUES ('1', 'Admin');
INSERT INTO `ai_role` VALUES ('1', 'Manager');
INSERT INTO `ai_role` VALUES ('1', 'Coder');
INSERT INTO `ai_role` VALUES ('2', 'CustomerService');

-- ----------------------------
-- Table structure for `ai_user`
-- ----------------------------
DROP TABLE IF EXISTS `ai_user`;
CREATE TABLE `ai_user` (
`id` bigint(18) NOT NULL AUTO_INCREMENT,
`user_name` varchar(55) NOT NULL,
`status` tinyint(5) NOT NULL DEFAULT '1',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4;

-- ----------------------------
-- Records of ai_user
-- ----------------------------
INSERT INTO `ai_user` VALUES ('1', 'Answer', '1');
INSERT INTO `ai_user` VALUES ('2', 'Iris', '1');


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