1. 数据渲染

template部分:
<a-cascader 
v-model:value="selected" 
:options="options" 
:load-data="loadData" 
placeholder="请选择" 
/>

js部分：
const options = ref<any>([])
// 接口请求
const getList = async (cat_id: string | number) => {
  let res = await cateListApi({ id })
  if (res.code === 0) {
    res.cont.forEach((item: any) => {
      options.value.push({
        label: item.name,
        value: item.id,
        isLeaf: item.isLeaf,
      })
    })
    return options.value
  }
}

onMounted(() => {
getList(0) // 接口请求第一层级数据
})

// load 根据点击数据获取下一级数据
const loadData = (selectedOptions: Option[]) => {
  const targetOption = selectedOptions[selectedOptions.length - 1];
  targetOption.loading = true;
  // load options lazily
  setTimeout(async () => {
    targetOption.loading = false;
    let res = await cateListApi({ id: targetOption.value })
    if (res.code === 0) {
      targetOption.children = res.cont.map((item: any) => {
        return {
          label: item.name,
          value: item.id,
          isLeaf: item.isLeaf,
        }
      })
      options.value = [...options.value];
    }
  }, 500);
};

2. 数据回显

比如接口返回数据为selected=[1, 11, 111] // 表示选择了第一个的三级数据

onMounted(() => {
	getParentNodes(selected, list.value) // 根据selected=[1, 11, 111]进行每一层数据获取
})

// 数据回显
const getParentNodes = async (ids: [], tree: []) => {
  for (let i = 0; i < ids.length - 1; i++) {
    tree.forEach(async (item: any) => {
      if (item.value === ids[i]) {
        item.children = []
        let data = []
        data = await cateListApi({ id: ids[i] })
        item.children = data.cont.map((child: any) => {
          return {
            label: child.catName,
            value: child.catId,
            isLeaf: child.isLeaf
          }
        })

        getParentNodes(ids, item.children)
      }
    })
  }
}