一、前端实现

1、参考 views/tree/index.vue

2、创建api

api/edu/subject.js

import request from '@/utils/request'
const api_name = '/admin/edu/subject'
export default {
  getNestedTreeList() {
    return request({
      url: `${api_name}`,
      method: 'get'
    })
  }
}

3、list.vue

<template>
  <div class="app-container">
    <el-input v-model="filterText" placeholder="Filter keyword" style="margin-bottom:30px;" />
    <el-tree
      ref="subjectTree"
      :data="subjectList"
      :props="defaultProps"
      :filter-node-method="filterNode"
      class="filter-tree"
      default-expand-all
    />
  </div>
</template>
<script>
import subject from '@/api/edu/subject'
export default {
  data() {
    return {
      filterText: '',
      subjectList: [],
      defaultProps: {
        children: 'children',
        label: 'title'
      }
    }
  },
  watch: {
    filterText(val) {
      this.$refs.subjectTree.filter(val)
    }
  },
  created() {
    this.fetchNodeList()
  },
  methods: {
    fetchNodeList() {
      subject.getNestedTreeList().then(response => {
        if (response.success === true) {
          this.subjectList = response.data.items
        }
      })
    },
    filterNode(value, data) {
      if (!value) return true
      return data.title.indexOf(value) !== -1
    }
  }
}
</script>

二、后端实现

1、创建vo

package com.guli.edu.vo;
@Data
public class SubjectVo {
    private String id;
    private String title;
}

package com.guli.edu.vo;
@Data
public class SubjectNestedVo {
    private String id;
    private String title;
    private List<SubjectVo> children = new ArrayList<>();
}

2、创建controller

@ApiOperation(value = "嵌套数据列表")
@GetMapping("")
public R nestedList(){
    List<SubjectNestedVo> subjectNestedVoList = subjectService.nestedList();
    return R.ok().data("items", subjectNestedVoList);
}

3、创建service

接口

List<SubjectNestedVo> nestedList();

实现Final

@Override
public List<SubjectNestedVo> nestedList() {
    //最终要的到的数据列表
    ArrayList<SubjectNestedVo> subjectNestedVoArrayList = new ArrayList<>();
    //获取一级分类数据记录
    QueryWrapper<Subject> queryWrapper = new QueryWrapper<>();
    queryWrapper.eq("parent_id", 0);
    queryWrapper.orderByAsc("sort", "id");
    List<Subject> subjects = baseMapper.selectList(queryWrapper);
    //获取二级分类数据记录
    QueryWrapper<Subject> queryWrapper2 = new QueryWrapper<>();
    queryWrapper2.ne("parent_id", 0);
    queryWrapper2.orderByAsc("sort", "id");
    List<Subject> subSubjects = baseMapper.selectList(queryWrapper2);
    //填充一级分类vo数据
    int count = subjects.size();
    for (int i = 0; i < count; i++) {
        Subject subject = subjects.get(i);
        //创建一级类别vo对象
        SubjectNestedVo subjectNestedVo = new SubjectNestedVo();
        BeanUtils.copyProperties(subject, subjectNestedVo);
        subjectNestedVoArrayList.add(subjectNestedVo);
        //填充二级分类vo数据
        ArrayList<SubjectVo> subjectVoArrayList = new ArrayList<>();
        int count2 = subSubjects.size();
        for (int j = 0; j < count2; j++) {
            Subject subSubject = subSubjects.get(j);
            if(subject.getId().equals(subSubject.getParentId())){
                //创建二级类别vo对象
                SubjectVo subjectVo = new SubjectVo();
                BeanUtils.copyProperties(subSubject, subjectVo);
                subjectVoArrayList.add(subjectVo);
            }
        }
        subjectNestedVo.setChildren(subjectVoArrayList);
    }
    return subjectNestedVoArrayList;
}

三、优化前端过滤功能

filterNode(value, data) {
    if (!value) return true
    return data.title.toLowerCase().indexOf(value.toLowerCase()) !== -1
}