在线教育项目-day07【课程分类显示接口】

前端

1.subject.js

import request from '@/utils/request'
export default {
    //1 课程分类列表
    getSubjectList() {
        return request({
            url: '/eduservice/edu-subject/getAllSubject',
            method: 'get'
          })
    }
}

2.list.vue

<template>
  <div class="app-container">
    <el-input v-model="filterText" placeholder="Filter keyword" style="margin-bottom:30px;" />

    <el-tree
      ref="tree2"
      :data="data2"
      :props="defaultProps"
      :filter-node-method="filterNode"
      class="filter-tree"
      default-expand-all
    />

  </div>
</template>

<script>
import subject from '@/api/subject/subject'
export default {

  data() {
    return {
      filterText: '',
      data2: [],  //返回所有分类数据
      defaultProps: {
        children: 'children',
        label: 'title'
      }
    }
  },
  created() {
      this.getAllSubjectList()
  },
  watch: {
    filterText(val) {
      this.$refs.tree2.filter(val)
    }
  },

  methods: {
    getAllSubjectList() {
        subject.getSubjectList()
            .then(response => {
                this.data2 = response.data.items
            })
    },
    filterNode(value, data) {
      if (!value) return true
      return data.title.toLowerCase().indexOf(value.toLowerCase()) !== -1
    }
  }
}
</script>

2.后端

controller

    @GetMapping("getAllSubject")
    public R nestedList(){

        List<OneSubject> subjectNestedVoList = eduSubjectService.nestedList();
        return R.OK().data("items", subjectNestedVoList);
    }

service

    List<OneSubject> nestedList();

serviceimpl

public List<OneSubject> nestedList() {
        //1 查询所有一级分类  parentid = 0
        QueryWrapper<EduSubject> wrapperOne = new QueryWrapper<>();
        wrapperOne.eq("parent_id","0");
        List<EduSubject> oneSubjectList = baseMapper.selectList(wrapperOne);

        //2 查询所有二级分类  parentid != 0
        QueryWrapper<EduSubject> wrapperTwo = new QueryWrapper<>();
        wrapperTwo.ne("parent_id","0");
        List<EduSubject> twoSubjectList = baseMapper.selectList(wrapperTwo);

        //创建list集合，用于存储最终封装数据
        List<OneSubject> finalSubjectList = new ArrayList<>();

        //3 封装一级分类
        //查询出来所有的一级分类list集合遍历，得到每个一级分类对象，获取每个一级分类对象值，
        //封装到要求的list集合里面 List<OneSubject> finalSubjectList
        for (int i = 0; i < oneSubjectList.size(); i++) { //遍历oneSubjectList集合
            //得到oneSubjectList每个eduSubject对象
            EduSubject eduSubject = oneSubjectList.get(i);
            //把eduSubject里面值获取出来，放到OneSubject对象里面
            OneSubject oneSubject = new OneSubject();
//            oneSubject.setId(eduSubject.getId());
//            oneSubject.setTitle(eduSubject.getTitle());
            //eduSubject值复制到对应oneSubject对象里面
            BeanUtils.copyProperties(eduSubject,oneSubject);
            //多个OneSubject放到finalSubjectList里面
            finalSubjectList.add(oneSubject);

            //在一级分类循环遍历查询所有的二级分类
            //创建list集合封装每个一级分类的二级分类
            List<TwoSubject> twoFinalSubjectList = new ArrayList<>();
            //遍历二级分类list集合
            for (int m = 0; m < twoSubjectList.size(); m++) {
                //获取每个二级分类
                EduSubject tSubject = twoSubjectList.get(m);
                //判断二级分类parentid和一级分类id是否一样
                if(tSubject.getParentId().equals(eduSubject.getId())) {
                    //把tSubject值复制到TwoSubject里面，放到twoFinalSubjectList里面
                    TwoSubject twoSubject = new TwoSubject();
                    BeanUtils.copyProperties(tSubject,twoSubject);
                    twoFinalSubjectList.add(twoSubject);
                }
            }
            //把一级下面所有二级分类放到一级分类里面
            oneSubject.setChildren(twoFinalSubjectList);
        }
        return finalSubjectList;
    }

最终测试