antd of vue treeSelect——异步加载

<a-tree-select
    style="width: 90%"
    allowClear
    :dropdown-style="{ maxHeight: '400px', overflow: 'auto' }"
    :treeData="personData"
    showSearch
    :load-data="onLoadData"
/>

onLoadData(treeNode){
   
    var that = this
    return new Promise((resolve) => {
   
        if (treeNode.