Refactoring Scene Data Model to Separate Session ID Using MyBatis in Java

Background: In a business scenario a single session_id may correspond to multiple scene_id and scene_name, and the original data structure repeats sessionId in each object.

Original VO class (redundant):

public class SceneVO {
  private String sessionId;
  private String sceneId;
  private String sceneName;
  // getters and setters omitted
}

Sample JSON returned by the original design:

{
  "data":[
    {"sessionId":"jksadhjksd","sceneId":"NDJWKSDSJKDKED","sceneName":"场景1"},
    {"sessionId":"jksadhjksd","sceneId":"KLJSDJKLSDFALK","sceneName":"场景2"},
    {"sessionId":"jksadhjksd","sceneId":"KERFJKOVDJKDSS","sceneName":"场景3"}
  ]
}

Desired JSON format moves sessionId to the outer level and nests scenes inside a sceneList array:

{
  "data": {
    "sessionId": "jksadhjksd",
    "sceneList": [
      {"sceneId":"NDJWKSDSJKDKED","sceneName":"场景1"},
      {"sceneId":"KLJSDJKLSDFALK","sceneName":"场景2"},
      {"sceneId":"KERFJKOVDJKDSS","sceneName":"场景3"}
    ]
  }
}

Entity classes to achieve the new structure:

public class SceneVO {
  private String sessionId;
  private List<SubSceneVO> sceneList;
  // getters and setters omitted
}

public class SubSceneVO {
  private String sceneId;
  private String sceneName;
  // getters and setters omitted
}

Custom MyBatis mapper interface and XML mapping:

public interface BusinessScenesCustomMapper {
  SceneVO selectBySessionId(String sessionId);
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="your.package.mapper.BusinessScenesCustomMapper">
  <resultMap id="BaseResultMap" type="your.package.vo.SceneVO">
    <result column="session_id" jdbcType="VARCHAR" property="sessionId"/>
    <!-- collection maps the repeated rows to a list of SubSceneVO -->
    <collection property="sceneList" ofType="your.package.vo.SubSceneVO">
      <result column="scene_id" jdbcType="VARCHAR" property="sceneId"/>
      <result column="scene_name" jdbcType="VARCHAR" property="sceneName"/>
    </collection>
  </resultMap>

  <select id="selectBySessionId" parameterType="string" resultMap="BaseResultMap">
    SELECT session_id, scene_id, scene_name
    FROM your_table
    WHERE session_id = #{sessionId,jdbcType=VARCHAR}
  </select>
</mapper>

Service layer that delegates to the mapper:

public interface SceneService {
  /** Get scene information for a given session */
  SceneVO getScenesInfo(String sessionId);
}

@Service
public class SceneServiceImpl implements SceneService {
  @Resource
  private BusinessScenesCustomMapper businessScenesCustomMapper;

  @Override
  public SceneVO getScenesInfo(String sessionId) {
    return businessScenesCustomMapper.selectBySessionId(sessionId);
  }
}

Controller exposing a REST endpoint:

@RestController
public class SceneController {
  @Resource
  private SceneService sceneService;

  @GetMapping("/getScenesInfo")
  public ResModel getScenesInfo(@RequestParam String sessionId) {
    SceneVO sceneVO = sceneService.getScenesInfo(sessionId);
    return ResModel.ok(sceneVO);
  }
}

With this refactoring, the API returns a compact JSON where the session identifier appears only once, and each scene is represented as an element of sceneList, simplifying front‑end consumption.