Mybatis实现树状结构查询
2024-10-21 09:53:28
1、实体类
@Data
public class CourseChapterVO implements Serializable {
private static final long serialVersionUID = -67718827554034368L;
/**
* 主键ID
*/
private Integer id;
/**
* 课程ID
*/
private Integer courseId;
/**
* 课程章节名称
*/
private String chapterName;
/**
* 父ID
*/
private Integer chapterParent;
/**
* 层级
*/
private Integer chapterLevel; @JsonInclude(JsonInclude.Include.NON_EMPTY) //当children为空时不返回
private List<CourseChapterVO> children;
}
2、mapper.xml
<resultMap type="com.ruoyi.manager.vo.CourseChapterVO" id="CourseChapterMap2">
<result property="id" column="id" jdbcType="INTEGER"/>
<result property="courseId" column="course_id" jdbcType="INTEGER"/>
<result property="chapterName" column="chapter_name" jdbcType="VARCHAR"/>
<result property="chapterParent" column="chapter_parent" jdbcType="INTEGER"/>
<result property="chapterLevel" column="chapter_level" jdbcType="INTEGER"/>
<collection property="children" ofType="com.ruoyi.manager.vo.CourseChapterVO" column="id" select="selectListTree2"/>
</resultMap> <select id="selectListTree1" resultMap="CourseChapterMap2">
select id , course_id, chapter_name, chapter_parent, chapter_level
from course_chapter where chapter_parent =0 </select> <select id="selectListTree2" resultMap="CourseChapterMap2">
select id , course_id, chapter_name, chapter_parent, chapter_level from course_chapter where chapter_parent =#{id}
</select>
3、mapper.java
List<CourseChapterVO> selectListTree1(CourseChapter courseChapter);
4、serviceImpl.java
@Override
public List<CourseChapterVO> queryAll(CourseChapter courseChapter) {
return this.courseChapterMapper.selectListTree1(courseChapter);
}
5、service.java
List<CourseChapterVO> queryAll(CourseChapter courseChapter);
6、controller.java
@GetMapping("list")
public R queryAll(CourseChapter courseChapter) {
return R.data(this.courseChapterService.queryAll(courseChapter));
}
7、实现效果
{
"msg": "",
"code": 0,
"data": [
{
"id": 1,
"courseId": 5,
"chapterName": "第一章节学习",
"chapterParent": 0,
"chapterLevel": 1,
"children": [
{
"id": 2,
"courseId": 5,
"chapterName": "第一章节学习子1",
"chapterParent": 1,
"chapterLevel": 2
},
{
"id": 3,
"courseId": 5,
"chapterName": "第一章节学习子2",
"chapterParent": 1,
"chapterLevel": 2
},
{
"id": 4,
"courseId": 5,
"chapterName": "第一章节学习子3",
"chapterParent": 1,
"chapterLevel": 2
}
]
},
{
"id": 5,
"courseId": 5,
"chapterName": "第二章节学习",
"chapterParent": 0,
"chapterLevel": 1,
"children": [
{
"id": 6,
"courseId": 5,
"chapterName": "第二章节学习子",
"chapterParent": 5,
"chapterLevel": 2,
"children": [
{
"id": 9,
"courseId": 5,
"chapterName": "第二章节学习子1子1",
"chapterParent": 6,
"chapterLevel": 3
}
]
},
{
"id": 7,
"courseId": 5,
"chapterName": "第二章节学习子1",
"chapterParent": 5,
"chapterLevel": 2
},
{
"id": 8,
"courseId": 5,
"chapterName": "第二章节学习子2",
"chapterParent": 5,
"chapterLevel": 2
}
]
},
{
"id": 10,
"courseId": 5,
"chapterName": "第三章节学习gfdgdf",
"chapterParent": 0,
"chapterLevel": 1
}
]
}
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